Adhesive optical film, manufacturing method for the same and image display device using the same

ABSTRACT

A pressure-sensitive adhesive optical film of the invention comprises an optical film and a pressure-sensitive adhesive layer provided on the optical film, wherein the pressure-sensitive adhesive layer has a thickness (μm) standard deviation of 0.12 μm or less. The pressure-sensitive adhesive optical film makes it possible to reduce the problem of visible unevenness caused by a pressure-sensitive adhesive layer.

TECHNICAL FIELD

The invention relates to a pressure-sensitive adhesive optical film anda producing method thereof. The invention also relates to an imagedisplay such as a liquid crystal display, an organic electroluminescence(EL) display, a cathode-ray tube (CRT), or a plasma display panel (PDP)produced using the pressure-sensitive adhesive optical film and to apart used together with an image display, such as a front face plate,produced using the pressure-sensitive adhesive optical film. Examples ofthe optical film that may be used include a polarizing plate, aretardation plate, an optical compensation film, a brightnessenhancement film, a surface treatment film such as an anti-reflectionfilm, and a laminate of any combination thereof.

The pressure-sensitive adhesive optical film may be a pressure-sensitiveadhesive polarizing plate including a polarizing plate as the opticalfilm. Such a pressure-sensitive adhesive polarizing plate may beprovided on the viewer side in an image display such as a liquid crystaldisplay or an organic electroluminescent (EL) display. In particular,such a pressure-sensitive adhesive polarizing plate is preferablyprovided as what is called an upper-side pressure-sensitive adhesivepolarizing plate on the viewer side of a liquid crystal cell in a liquidcrystal display. The upper-side pressure-sensitive adhesive polarizingplate used in the liquid crystal display is bonded to the liquid crystalcell with the pressure-sensitive adhesive layer interposed therebetween.

DESCRIPTION OF THE RELATED ART

Liquid crystal displays, organic EL displays, etc. have an image-formingmechanism including polarizing elements as essential components. Forexample, therefore, in a liquid crystal display, polarizing elements areessentially placed on both sides of a liquid crystal cell, andgenerally, polarizing plates which include a polarizer and a transparentprotective film bonded on one side or both sides of the polarizer areattached as the polarizing elements. Besides polarizing plates, variousoptical elements have been used in display panels such as liquid crystalpanels and organic EL panels for improving display quality. Front faceplates are also used to protect image displays such as liquid crystaldisplays, organic EL displays, CRTs, and PDPs or to provide a high-gradeappearance or a differentiated design. Examples of parts used in imagedisplays such as liquid crystal displays and organic EL displays orparts used together with image displays, such as front face plates,include retardation plates for preventing discoloration, viewingangle-widening films for improving the viewing angle of liquid crystaldisplays, brightness enhancement films for increasing the contrast ofdisplays, and surface treatment films such as hard-coat films for use inimparting scratch resistance to surfaces, antiglare treatment films forpreventing glare on image displays, and anti-reflection films such asanti-reflective films and low-reflective films. These films aregenerically called optical films.

A display panel such as the liquid crystal panel or the organic EL panelis used in a liquid crystal display or an organic EL display for clocks,cellular phones, personal digital assistants (PDAs), note PCs, PCmonitors, DVD players, TVs, etc. A liquid crystal panel has polarizingplates as optical films provided on both sides of a liquid crystal cell(upper side: viewer side, lower side: side opposite to the viewer sideor backlight side) according to the display mechanism of a liquidcrystal display. A common polarizing plate includes a polarizer and atransparent protective film or films provided on one or both sides ofthe polarizer. In recent years, display panels such as liquid crystalpanels and organic EL panels have been required to have more improveddisplay characteristics, such as higher brightness, higher definition,and lower reflection. Optical films for use in display panels suchliquid crystal panels and organic EL panels have also been required tohave a higher level of appearance.

When such optical films are bonded to a display panel such as a liquidcrystal cell or an organic EL panel or bonded to a front face plate, apressure-sensitive adhesive is generally used. In the process of bondingan optical film to a display panel such as a liquid crystal cell or anorganic EL panel or to a front faceplate or bonding optical filmstogether generally reduce optical loss. Therefore, a pressure-sensitiveadhesive is used to bond the materials together. In such a case, apressure-sensitive adhesive optical film including an optical film and apressure-sensitive adhesive layer previously formed on one side of theoptical film is generally used, because it has some advantages such asno need for a drying process to fix the optical film.

It is proposed that the surface state of the pressure-sensitive adhesivelayer should be controlled from various aspects. For example, it isproposed that the standard deviation for variations in the thickness ofa pressure-sensitive adhesive layer provided on a polarizing plate orthe like should be reduced so that durability in a high-temperature orhigh-temperature, high-humidity environment can be improved (PatentDocument 1). It is also proposed that the surface roughness of apressure-sensitive adhesive layer should be controlled so thatunevenness of the pressure-sensitive adhesive can be reduced and thatvisibility can be improved (Patent Document 2).

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: JP-A-09-90125-   Patent Document 2: JP-A-2008-302580

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

Patent Documents 1 and 2 propose that the surface state of apressure-sensitive adhesive layer should be controlled. Unfortunately,Patent Document 1 does not disclose any specific process for forming apressure-sensitive adhesive layer, although it discloses that a solventcasting method can be used to form a pressure-sensitive adhesive layerwith a small standard deviation. The disclosure in Patent Document 1cannot make it possible to form a pressure-sensitive adhesive layer witha substantially small standard deviation. Patent Document 2 disclosescontrolling the surface roughness of a pressure-sensitive adhesivelayer, but does not disclose that variations in the thickness of apressure-sensitive adhesive layer are controlled to be small.

In a conventional upper-side polarizing plate, the viewer side of apolarizer is provided with a transparent protective film havingundergone an antiglare treatment for providing a high haze value. Thus,any irregularities on the polarizing plate or the pressure-sensitiveadhesive layer are not clearly visible as unevenness because theantiglare treated transparent protective film has a high haze value.

On the other hand, in recent years, liquid crystal displays,specifically, liquid crystal panels for TVs, note PCs, or PC monitors,have been desired to have a brightness-enhanced uppermost surface, whatis called a clear high-grade appearance. Such a clear-type liquidcrystal display is produced using a front face plate such as a glass oracrylic plate, which is placed to form the uppermost surface of theliquid crystal display. Unfortunately, the use of the front face plateundesirably increases cost and weight. When the clear-type liquidcrystal display is produced, the transparent protective film used on theviewer side of the polarizer in the upper side polarizing plate has notundergone an antiglare treatment or has undergone an antiglare treatmentfor providing a low haze value. However, when such a transparentprotective film having undergone no antiglare treatment or alow-haze-value antiglare treatment is used, irregularities on thepolarizing plate or the pressure-sensitive adhesive layer are madevisible by reflection, which would otherwise be invisible if aconventional transparent protective film with a high haze value is used.

There also have been an increasing number of liquid crystal displaymodels having a front face plate or a touch panel on the viewer side. Insuch a structure, a pressure-sensitive adhesive layer-carrying surfacetreatment film is sometimes bonded to the front face plate or the touchpanel in order to suppress a reduction in visibility caused byreflection at the interface between the air layer and the front faceplate or the touch panel. Unfortunately, as described above, theconventional pressure-sensitive adhesive optical film has relativelylarge surface irregularities due to variations in the thickness of theoptical film and the pressure-sensitive adhesive layer. In recent years,as a surface treatment for a low-haze clear appearance becomes a mainstream, a problem has arisen in which a clear appearance is degraded dueto irregularities on a pressure-sensitive adhesive layer and an opticalfilm. Thus, a pressure-sensitive adhesive layer-carrying surfacetreatment film also has been required to have a smoothpressure-sensitive adhesive layer with no irregularities.

It is an object of the invention to provide a pressure-sensitiveadhesive optical film that includes an optical film and apressure-sensitive adhesive layer and makes it possible to reduce theproblem of visible unevenness caused by a pressure-sensitive adhesivelayer, and to provide a method for producing such a pressure-sensitiveadhesive optical film.

It is another object of the invention to provide a pressure-sensitiveadhesive polarizing plate as the pressure-sensitive adhesive opticalfilm, which includes a polarizing plate and a pressure-sensitiveadhesive layer, has a clear high-grade appearance, and makes it possibleto reduce the problem of visible unevenness caused by apressure-sensitive adhesive polarizing plate, and to provide a methodfor producing such a pressure-sensitive adhesive polarizing plate.

It is further object of the invention is to provide an image displayincluding the pressure-sensitive adhesive optical film.

Means for Solving the Problems

As a result of earnest studies to solve the above problems, theinventors have accomplished the invention based on the finding thepressure-sensitive adhesive optical film etc., described below can solvethe problems.

The invention relates to a pressure-sensitive adhesive optical film,comprising an optical film and a pressure-sensitive adhesive layerprovided on the optical film, wherein the pressure-sensitive adhesivelayer has a thickness (μm) standard deviation of 0.12 μm or less.

In the pressure-sensitive adhesive optical film, the optical film ismentioned a polarizing plate comprising a polarizer and a firsttransparent protective film provided on one side of the polarizer orfirst and second transparent protective films provided on both sides ofthe polarizer (hereinafter, the pressure-sensitive adhesive optical filmusing the polarizing plate as the optical film is called apressure-sensitive adhesive polarizing plate),

the first transparent protective film has a haze value of 15% or less,and

the pressure-sensitive adhesive layer is provided on a side of thepolarizing plate opposite to a side where the first transparentprotective film is provided.

In the pressure-sensitive adhesive polarizing plate, the firsttransparent protective film preferably has a thickness of 60 μm or less.

In the pressure-sensitive adhesive polarizing plate, the polarizingplate preferably has first and second transparent protective films onboth sides of the polarizer, and at least one of the first and secondtransparent protective films has a thickness of 60 μm or less.

In the pressure-sensitive adhesive polarizing plate, the polarizerpreferably has a thickness of 10 μm or less.

In the pressure-sensitive adhesive optical film, the optical film may bea retardation plate. The retardation plate preferably has a thickness of60 μm or less.

In the pressure-sensitive adhesive optical film, the optical filmpreferably has a haze value of 15% or less. The optical film ispreferably used as intended to be bonded to a front face plate or atouch panel.

The optical film, which has a haze value of 15% or less, preferably hasa thickness of 60 μm or less. The optical film, which has a haze valueof 15% or less, is preferably a surface treatment film.

The invention also relates to a method for producing thepressure-sensitive adhesive optical film comprising an optical film anda pressure-sensitive adhesive layer provided on the optical film, themethod comprising the steps of:

(1A) applying a pressure-sensitive adhesive coating liquid with aviscosity Y (P) to the optical film to form a coating with a thickness X(μm); and

(2A) drying the applied pressure-sensitive adhesive coating liquid toform a pressure-sensitive adhesive layer, wherein

the viscosity Y of the pressure-sensitive adhesive coating liquid andthe thickness X of the coating satisfy the relation 0.8X−Y≦68.

The invention also relates to a method for producing thepressure-sensitive adhesive optical film comprising an optical film anda pressure-sensitive adhesive layer provided on the optical film, themethod comprising the steps of:

(1B) applying a pressure-sensitive adhesive coating liquid with aviscosity Y (P) to a release film to form a coating with a thickness X(μm);

(2B) drying the applied pressure-sensitive adhesive coating liquid toform a pressure-sensitive adhesive layer; and

(3) bonding the pressure-sensitive adhesive layer, which is formed onthe release film, to the optical film, wherein

the viscosity Y of the pressure-sensitive adhesive coating liquid andthe thickness X of the coating satisfy the relation 0.8X−Y≦68.

In the method for producing the pressure-sensitive adhesive opticalfilm, the pressure-sensitive adhesive coating liquid preferably has aviscosity Y (P) of 2 to 160 P, and the coating has a thickness X (μm) of20 to 250 μm.

The invention also relates to a pressure-sensitive adhesive opticalfilm, comprising at least two optical films and at least twopressure-sensitive adhesive layers alternately laminated, wherein

at least one of the pressure-sensitive adhesive layers has a thickness(μm) standard deviation of 0.12 μm or less (hereinafter, thepressure-sensitive adhesive optical film is called a laminatedpressure-sensitive adhesive polarizing plate).

In the laminated pressure-sensitive adhesive optical film, each of theat least two pressure-sensitive adhesive layers preferably has athickness (μm) standard deviation of 0.12 μm or less.

In the laminated pressure-sensitive adhesive optical film, one of theoptical films is mentioned a polarizing plate comprising a polarizer anda first transparent protective film provided on one side of thepolarizer or first and second transparent protective films provided onboth sides of the polarizer (hereinafter, the laminatedpressure-sensitive adhesive optical film using the polarizing plate asone of the optical film is called a laminated pressure-sensitiveadhesive polarizing plate),

the first transparent protective film has a haze value of 15% or less,and

the pressure-sensitive adhesive layer is provided on a side of thepolarizing plate opposite to a side where the first transparentprotective film is provided.

In the laminated pressure-sensitive adhesive polarizing plate, the firsttransparent protective film preferably has a thickness of 60 μm or less.

In the laminated pressure-sensitive adhesive polarizing plate, thepolarizing plate preferably has first and second transparent protectivefilms on both sides of the polarizer, and at least one of the first andsecond transparent protective films has a thickness of 60 μm or less.

In the laminated pressure-sensitive adhesive polarizing plate, thepolarizer preferably has a thickness of 10 μm or less.

In the laminated pressure-sensitive adhesive optical film, preferably,one of the optical films is a polarizing plate comprising a polarizerand a first transparent protective film provided on one side of thepolarizer or first and second transparent protective films provided onboth sides of the polarizer,

the first transparent protective film has a haze value of 15% or less,

the pressure-sensitive adhesive layer is provided on a side of thepolarizing plate opposite to a side where the first transparentprotective film is provided, and

at least one of the other optical film or films is a retardation plate.The retardation plate preferably has a thickness of 60 μm or less.

The invention also relates to an image display, comprising at least onepiece of the pressure-sensitive adhesive optical film (or the laminatedpressure-sensitive adhesive optical film).

Effects of the Invention

In the pressure-sensitive adhesive optical film (or the laminatedpressure-sensitive adhesive optical film) of the invention, thethickness (μm) of the pressure-sensitive adhesive layer is controlled tohave a standard deviation of 0.12 μm or less. Thus, thepressure-sensitive adhesive layer is highly smooth and has a very lowlevel of irregularities in thickness. Surface irregularities of apressure-sensitive adhesive optical film are caused by variations in thethickness of its pressure-sensitive adhesive layer and its optical film.The pressure-sensitive adhesive optical film of the invention makes itpossible to reduce unevenness caused by irregularities on the opticalfilm and the pressure-sensitive adhesive layer.

The invention is based on the finding that irregularities in thethickness of a pressure-sensitive adhesive layer are caused by flowingof a pressure-sensitive adhesive coating liquid during drying. Thus,increasing the viscosity Y of a pressure-sensitive adhesive coatingliquid or decreasing the coating thickness X of the pressure-sensitiveadhesive coating liquid makes it possible to reduce flowing of thepressure-sensitive adhesive coating liquid, and forming apressure-sensitive adhesive layer in such a manner that the thickness Xand the viscosity Y satisfy the specified relation enablesirregularities in the thickness of the pressure-sensitive adhesive layerto be controlled to a low level.

The pressure-sensitive adhesive optical film (or the laminatedpressure-sensitive adhesive optical film) may be a pressure-sensitiveadhesive polarizing plate (or a laminated pressure-sensitive adhesivepolarizing plate). In this case, the pressure-sensitive adhesivepolarizing plate (or laminated pressure-sensitive adhesive polarizingplate) may have a transparent protective film with a haze value of 15%or less for forming the uppermost surface of an image display such as aliquid crystal display or an organic EL display (a transparentprotective film for forming the uppermost surface of an upper-sidepolarizing plate in a liquid crystal display), so that an image display,such as a liquid crystal display or an organic EL display, having aclear high-grade appearance can be provided without using any front faceplate. In the pressure-sensitive adhesive polarizing plate, thethickness (μm) of the pressure-sensitive adhesive layer is controlled tohave a standard deviation of 0.12 μm or less. Thus, thepressure-sensitive adhesive layer is highly smooth and has a very lowlevel of irregularities in thickness. The use of the pressure-sensitiveadhesive polarizing plate of the invention makes it possible to preventvisible unevenness, which would otherwise be caused by irregularities ona pressure-sensitive adhesive polarizing plate, and to impart a clearhigh-grade appearance to an image display such as a liquid crystaldisplay.

The optical film (e.g., a surface treatment film) used in thepressure-sensitive adhesive optical film may have a haze of 15% or less.In this case, the pressure-sensitive adhesive optical film may be bondedto a front face plate, so that the front face plate can provide a clearhigh-grade appearance, while the pressure-sensitive adhesive layer witha controlled standard deviation of 0.12 μm or less provides no visibleirregularities-induced unevenness, which makes it possible to impart aclear high-grade appearance to an image display such as a liquid crystaldisplay or an organic EL display.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing an example of thepressure-sensitive adhesive optical film of the invention.

FIG. 2 is a cross-sectional view showing an example of thepressure-sensitive adhesive optical film of the invention.

FIG. 3 is a cross-sectional view showing an example of thepressure-sensitive adhesive optical film of the invention.

FIG. 4 is a cross-sectional view showing an example of the laminatedpressure-sensitive adhesive optical film of the invention.

FIG. 5 is a cross-sectional view showing an example of the laminatedpressure-sensitive adhesive optical film of the invention.

FIG. 6 is a cross-sectional view showing an example of the laminatedpressure-sensitive adhesive optical film of the invention.

FIG. 7 is a cross-sectional view showing an example of the laminatedpressure-sensitive adhesive optical film of the invention.

FIG. 8 is a cross-sectional view showing an example of how to use thepressure-sensitive adhesive optical film of the invention.

FIG. 9 is a cross-sectional view showing an example of how to use thepressure-sensitive adhesive optical film of the invention.

FIG. 10 is a cross-sectional view showing an example of how to use thepressure-sensitive adhesive optical film of the invention.

FIG. 11 is a schematic diagram showing a process of producing a thinhigh-performance polarizing film.

FIG. 12 is a schematic diagram showing a process of producing a thinhigh-performance polarizing film and processes including dry stretching.

FIG. 13 shows a table for a comparison between the optical properties ofthe thin high-performance polarizing films of reference productionexamples and the films of reference comparative examples.

FIG. 14 shows tables of the T/P values of the thin high-performancepolarizing films of reference production examples and the films ofreference comparative examples.

FIG. 15 is a T-P graph based on the T/P values of the thinhigh-performance polarizing films of reference production examples andthe films of reference comparative examples.

FIG. 16 is a schematic T-P graph for thin high-performance polarizingfilms.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the pressure-sensitive adhesive optical film of theinvention is described with reference to the drawings. As shown in FIG.1, the pressure-sensitive adhesive optical film includes an optical film1 and a pressure-sensitive adhesive layer 2 provided on the optical film1. The pressure-sensitive adhesive layer 2 has a thickness (μm) standarddeviation of 0.12 μm or less. The optical film 1 may be any of variousoptical films such as a polarizing plate, a retardation plate, anoptical compensation film, a brightness enhancement film, and a surfacetreatment film such as an anti-reflection film. FIGS. 2 to 10 illustratedifferent modes of the optical film.

FIGS. 2 and 3 show cases where the pressure-sensitive adhesive opticalfilm of the invention is a pressure-sensitive adhesive polarizing plate.The pressure-sensitive adhesive polarizing plate includes a polarizingplate A1 or A2, which corresponds to the optical film 1, and apressure-sensitive adhesive layer 2 provided on the polarizing plate A1or A2. In a liquid crystal display, the pressure-sensitive adhesivepolarizing plate is disposed on the viewer side of a liquid crystal cellwith the pressure-sensitive adhesive layer 2 interposed therebetween.The polarizing plate A1 or A2 includes a polarizer (a) and a firsttransparent protective film (b1) provided on one side of the polarizer(a) or first and second transparent protective films (b1) and (b2)provided on both sides of the polarizer (a). In the case of FIG. 2, thepolarizing plate A1 has a first transparent protective film (b1) on onlyone side of the polarizer (a). In the case of FIG. 3, the polarizingplate A2 has first and second transparent protective films (b1) and (b2)on both sides of the polarizer (a). The polarizing plate A1 or A2 has atleast the first transparent protective film (b1), and the firsttransparent protective film (b1) side corresponds to the uppermostsurface in an image display such as a liquid crystal display and anorganic EL display. In FIGS. 2 and 3, the pressure-sensitive adhesivelayer 2 is provided on a side of the polarizing plate A1 or A2 oppositeto its side where the first transparent protective film (b1) isprovided. Specifically, when a first transparent protective film 1 b isprovided on only one side of the polarizer (a) as shown in FIG. 2, thepressure-sensitive adhesive layer 1 b is provided on the polarizer (a),and when first and second transparent protective films (b1) and (b2) areprovided on both sides of the polarizer (a), the pressure-sensitiveadhesive layer 2 is provided on the second transparent protective film(b2).

FIGS. 4 to 7 each show a laminated pressure-sensitive adhesive opticalfilm in which at least two optical films 1 and at least twopressure-sensitive adhesive layers 2 are alternately laminated. In FIGS.4 to 7, a retardation plate B, which corresponds to the optical film 1,is placed on the pressure-sensitive adhesive layer 2 of thepressure-sensitive adhesive polarizing plate of FIG. 2 or 3, and anotherpressure-sensitive adhesive layer 2 is provided on the retardation plateB. In FIG. 4, a first pressure-sensitive adhesive layer 21, a firstretardation plate B1, and a second pressure-sensitive adhesive layer 22are provided in this order on the second transparent protective film(b2) of the polarizing plate A1 of FIG. 2. In FIG. 6, a secondretardation plate B2 and a third pressure-sensitive adhesive layer 23are further provided in this order on the second pressure-sensitiveadhesive layer 22. In FIG. 5, a first pressure-sensitive adhesive layer21, a first retardation plate B1, and a second pressure-sensitiveadhesive layer 22 are provided in this order on the polarizer (a) of thepolarizing plate A2 of FIG. 3. In FIG. 6, a second retardation plate B2and a third pressure-sensitive adhesive layer 23 are further provided inthis order on the second pressure-sensitive adhesive layer 22. In thelaminated pressure-sensitive adhesive optical film, at least onepressure-sensitive adhesive layer 2 has a thickness (μm) standarddeviation of 0.12 μm or less. Preferably, each pressure-sensitiveadhesive layer 2 has a thickness (μm) standard deviation of 0.12 μm orless.

FIGS. 8 to 10 show modes of the use of a pressure-sensitive adhesivesurface treatment film having a surface treatment film C, which is usedas the optical film 1 in the pressure-sensitive adhesive optical film ofthe invention. The surface treatment film C includes a base film whoseone side is surface-treated. In the pressure-sensitive adhesive surfacetreatment film, the pressure-sensitive adhesive layer 2 is provided onthe non-surface-treated side of the base film. FIG. 8 shows a mode wherethe pressure-sensitive adhesive layer 2 of the pressure-sensitiveadhesive surface treatment film is bonded to a front face plate F. FIG.9 shows a case where a touch panel T is further provided on the frontface plate T in the mode of FIG. 8. FIG. 10 shows a mode where thepressure-sensitive adhesive layer 2 of the pressure-sensitive adhesivesurface treatment film is bonded to a touch panel T. In FIG. 10, a frontface plate F is further provided on the touch panel T. In all casesshown in FIGS. 8 to 10, the pressure-sensitive adhesive surfacetreatment film C is bonded to the front face plate F, the touch panel T,or the like in such a manner that the surface treatment film C forms thesurface on one side. The pressure-sensitive adhesive surface treatmentfilm C bonded to the front face plate F, the touch panel T, or the likeis placed on the viewer side of an image display such as a liquidcrystal display and an organic EL display. It may be bonded in such amanner that the surface treatment film C side is located on the imagedisplay side or on the uppermost surface side opposite to the imagedisplay side.

A polarizer, which is applied to the invention, is not limitedespecially but various kinds of polarizer may be used. As a polarizer,for example, a film that is uniaxially stretched after havingdichromatic substances, such as iodine and dichromatic dye, absorbed tohydrophilic high molecular weight polymer films, such as polyvinylalcohol-based film, partially formalized polyvinyl alcohol-based film,and ethylene-vinyl acetate copolymer-based partially saponified film;poly-ene-based alignment films, such as dehydrated polyvinyl alcohol anddehydrochlorinated polyvinyl chloride, etc. may be mentioned. In these,a polyvinyl alcohol-based film on which dichromatic materials such asiodine, is absorbed and aligned after stretched is suitably used.Although thickness of polarizer is not especially limited, the thicknessof about 80 μm or less is commonly adopted. The thickness is preferablyfrom 10 to 50 μm, more preferably from 15 to 30 μm.

A polarizer that is uniaxially stretched after a polyvinyl alcohol-basedfilm dyed with iodine is obtained by stretching a polyvinylalcohol-based film by 3 to 7 times the original length, after dipped anddyed in aqueous solution of iodine. If needed the film may also bedipped in aqueous solutions, such as boric acid and potassium iodide,which may include zinc sulfate, zinc chloride. Furthermore, beforedyeing, the polyvinyl alcohol-based film may be dipped in water andrinsed if needed. By rinsing polyvinyl alcohol-based film with water,effect of preventing un-uniformity, such as unevenness of dyeing, isexpected by making polyvinyl alcohol-based film swelled in addition thatalso soils and blocking inhibitors on the polyvinyl alcohol-based filmsurface may be cleaned off. Stretching may be applied after dyed withiodine or may be applied concurrently, or conversely dyeing with iodinemay be applied after stretching. Stretching is applicable in aqueoussolutions, such as boric acid and potassium iodide, and in water bath.

A thin polarizer with a thickness of 10 μm or less may also be used. Inview of thinning, the thickness is preferably from 1 to 7 μm. Such athin polarizer is less uneven in thickness, has good visibility, and isless dimensionally-variable and therefore has high durability. It isalso preferred because it can form a thinner polarizing film.

Typical examples of such a thin polarizer include the thin polarizingfilms disclosed in JP-A No. 51-069644, JP-A No. 2000-338329,WO2010/100917, specification of PCT/JP2010/001460, specification ofJapanese Patent Application No. 2010-269002, or specification ofJapanese Patent Application No. 2010-263692. These thin polarizing filmscan be obtained by a process including the processes of stretching alaminate of a polyvinyl alcohol-based resin (hereinafter also referredto as PVA-based resin) layer and a stretchable resin substrate anddyeing the laminate. Using this process, the PVA-type resin layer, evenwhen thin, can be stretched without problems such as breakage, whichwould otherwise be caused by stretching of the layer supported on astretchable resin substrate.

Among processes including the processes of stretching and dyeing alaminate, a process capable of high-ratio stretching to improvepolarizing performance is preferably used to obtain the thin polarizingfilm. Therefore, the thin polarizing film is preferably obtained by aprocess including the step of stretching in an aqueous boric acidsolution as disclosed in WO2010/100917, the specification ofPCT/JP2010/001460, the specification of Japanese Patent Application No.2010-269002, or the specification of Japanese Patent Application No.2010-263692, in particular, preferably obtained by a process includingthe step of performing auxiliary in-air stretching before stretching inan aqueous boric acid solution as disclosed in the specification ofJapanese Patent Application No. 2010-269002 or the specification ofJapanese Patent Application or 2010-263692.

The specification of PCT/JP2010/001460 discloses a thin high-performancepolarizing film that is formed integrally with a resin substrate, madeof a PVA-based resin containing an oriented dichroic material, and has athickness of 7 μm or less and the optical properties of a singletransmittance of 42.0% or more and a polarization rate of 99.95% ormore.

The thin high-performance polarizing film described in PCT/JP2010/001460is preferably used as the thin polarizer.

The thin high-performance polarizing film includes a polyvinylalcohol-based resin (hereinafter also referred to as “PVA-based resin”)with a thickness of 7 μm or less, which is formed integrally with aresin substrate and contains an oriented dichroic material. The thinhigh-performance polarizing film has the optical properties of a singletransmittance of 42.0% or more and a polarization rate of 99.95% ormore. The thickness is preferably from 2 to 6 μm.

This thin high-performance polarizing film can be produced by a processincluding forming a PVA-based resin coating on a resin substrate with athickness of at least 20 μm, drying the coating to form a PVA-type resinlayer, immersing the resulting PVA-type resin layer in a dyeing liquidcontaining a dichroic material to absorb the dichroic material to thePVA-type resin layer, and stretching the PVA-type resin layer, whichcontains the absorbed dichroic material, together with the resinsubstrate in an aqueous boric acid solution to a total stretch ratio of5 times or more the original length.

A laminate film having a thin high-performance polarizing filmcontaining an oriented dichroic material can be produced by a methodincluding the processes of: coating a PVA-based resin-containing aqueoussolution to one side of a resin substrate with a thickness of at least20 μm, drying the coating to form a PVA-type resin layer so that alaminate film including the resin substrate and the PVA-type resin layerformed thereon is produced; immersing the laminate film in a dyeingliquid containing a dichroic material to absorb the dichroic material tothe PVA-type resin layer in the laminate film, wherein the laminate filmincludes the resin substrate and the PVA-type resin layer formed on oneside of the resin substrate; and stretching the laminate film, which hasthe PVA-type resin layer containing the absorbed dichroic material, inan aqueous boric acid solution to a total stretch ratio of 5 times ormore the original length, wherein the PVA-type resin layer containingthe absorbed dichroic material is stretched together with the resinsubstrate, so that a laminate film including the resin substrate and athin high-performance polarizing film formed on one side of the resinsubstrate is produced, in which the thin high-performance polarizingfilm is made of the PVA-type resin layer containing the orienteddichroic material and has a thickness of 7 μm or less and the opticalproperties of a single transmittance of 42.0% or more and a polarizationrate of 99.95% or more.

Herein, background art related to optical properties should besummarized. In brief, the optical properties of polarizing filmssuitable for use in large displays can be expressed using degree P ofpolarization and single transmittance T. The performance of a polarizingfilm is usually expressed by a T-P graph plotted with degree P ofpolarization and single transmittance T, which are two opticalcharacteristic values in trade-off relationship.

Refer to the schematic graph of FIG. 16. T=50% and P=100% are idealproperties. When the T value is low, it is easy to increase the P value,and when the T value is high, it is difficult to increase the P value.Thus, a degree P of polarization of 99.95% or more and a singletransmittance T of 42.0% or more are optical properties desired now orin the future for the performance of a polarizing film for use in alarge display or any other device, while such properties have not beenachieved yet. It should be noted that while ideal properties are T=50%and P=100%, light is partially reflected at the interface between apolarizing film and air when passing through the polarizing film. Takingthis reflection phenomenon into account, the transmittance is reduced bythe part of the reflection, and thus the practically achievable maximumT value would be from about 45 to 46%.

The degree P of polarization can indicate the contrast ratio (CR) of apolarizing film or a display. A degree P of polarization of 99.95%corresponds to a CR of 2,000:1 for a polarizing film, which correspondsto a CR of 1,050:1 for a display produced using such a polarizing filmand a common commercially-available liquid crystal television cell. Inany case, the larger CR means the higher display contrast and the highervisibility. As described below, the CR of a polarizing film is a valueobtained by dividing the parallel transmittance by the crosstransmittance. The CR of a display is a value obtained by dividing themaximum brightness by the minimum brightness. The minimum brightness isdefined as the level of brightness when black is displayed, which isrequired to be 0.5 cd/m² or less for a liquid crystal televisionintended to be used in a common audio-visual environment. If it exceedsthis value, color reproducibility can decrease. The maximum brightnessis defined as the level of brightness when white is displayed, which isin the range of 450 to 550 cd/cm² for a liquid crystal televisionintended to be used in a common audio-visual environment. If it is lessthan the range, visibility can decrease.

It is thus thought that liquid crystal televisions usually need to havea CR of 1,000:1 or more. On the other hand, a polarizing film needs tohave a CR of 2,000:1 or more in view of depolarization in a liquidcrystal cell. This corresponds to a degree P of polarization of 99.95%or more.

Polarizing films generally used in liquid crystal televisions have asingle transmittance T of 42.0% or more. The brightness L of a displaycan be relatively low when a polarizing film with a single transmittanceT of less than 42.0% is used. For example, when the brightness L of adisplay produced using a polarizing film with T=42.0% is normalized as100, a display produced using a polarizing film with T=40.0% has abrightness L of 90. This means that to ensure a display brightness L of100 at T=42.0%, the lighting energy of a light source during use must beincreased by 10% in a display produced using a polarizing film withT=40.0%. In view of the light source used in the display, this suggeststhat the display brightness L must be increased by increasing thebrightness L of the light source itself in order for the display to beequivalent to that produced using a polarizing film with a singletransmittance T of 42.0%.

The use of the thin high-performance polarizing film and the method forproduction thereof make it possible to provide a thin polarizing filmwith a high level of optical properties.

Conventional methods for producing a thin polarizing film need toperform dry stretching using a stretching machine in a heating apparatussuch as an oven. It is difficult for dry stretching to stretch alaminate of a resin substrate and a PVA-type resin layer to 5 times ormore its original length because crystallization of the resin substrateand the PVA-type resin layer formed thereon proceeds in the process.This crystallization phenomenon similarly occurs when a thick polarizingfilm is produced by dry-stretching a monolayer material. Dichroicmaterials cannot be sufficiently oriented due to the crystallization ofthe PVA-type resin layer and the limitation on stretch ratio. This was afirst technical problem.

As a matter of course, so far there has been developed no thinpolarizing film having optical properties comparable to those of a thickpolarizing film produced through wet stretching. PVA-based resin is ahydrophilic polymer composition, which is highly soluble in water. Ithas been a problem how to make a thin PVA-type resin layer insoluble inan aqueous solution, how to highly orient an adsorbed dichroic materialby high-ratio stretching, and, thus, how to achieve a thin polarizingfilm with a high level of optical properties.

A thin PVA-type resin layer formed on a resin substrate by applying anaqueous solution of a PVA-based resin thereto and drying it can bestretched to a high ratio (5 times or more) together with the resinsubstrate in an aqueous boric acid solution at a low temperature (65° C.or less). More specifically, in an aqueous boric acid solution at a lowtemperature (65° C. or less), a thin PVA-type resin layer formed on aresin substrate can be insolubilized by a crosslinking reaction, andthen the insolubilized thin PVA-type resin layer can be stretched to 5times or more together with the resin substrate.

Surprisingly, it has also been found that since water molecules play arole as a plasticizer, a thin PVA-type resin layer can be stretched to ahigh ratio together with a resin substrate even in an aqueous boric acidsolution at a temperature lower than the glass transition temperature ofthe resin substrate. Based on this finding, a PVA-based resin can bestretched to a high ratio while crystallization of the resin issuppressed, so that a thin polarizing film containing a dichroicmaterial oriented and adsorbed sufficiently, what is called a thinhigh-performance polarizing film, can be obtained for use in a largedisplay, as shown in Reference Production Examples 1 and 2 where thethin high-performance polarizing films of FIG. 14 or 15 are produced.The thin high-performance polarizing film, processes used in the methodfor production thereof, and the effects of the processes are describedbelow.

(a) Effect of Stretching in an Aqueous Boric Acid Solution at LowTemperature (65° C. or Less)

In order to stretch a thin PVA-based resin film with a thickness of afew ten μm or less to a high ratio in an aqueous solution, the PVA-basedresin film must stand the tension applied during the stretching, evenwhen formed on a resin substrate with a thickness of 20 μm or more, andmust have water resistance so as to be insoluble in water during thestretching. Thus, the PVA-based resin film must be insolubilized.

Boric acid produces tetrahydroxyborate anions in an aqueous solution asshown in the following formula.

H₃BO₃+H₂O←→H⁺+[B(OH)₄]⁻

It can be hypothesized that the tetrahydroxyborate anions form hydrogenbonds with the hydroxy groups of a vinyl alcohol-based polymer tocrosslink the vinyl alcohol-based polymer. The state shown in ChemicalFormula (1) can be provided as a hypothetical model for the crosslinkedstate (in Chemical Formula (1), dotted lines represent crosslinks. Thecrosslinkage insolubilizes the vinyl alcohol-based polymer.

When a PVA-based resin is stretched in an aqueous boric acid solution,the PVA-type resin layer is successfully insolubilized, so that it canbe stretched to a high stretch ratio of 5 times or more.

(b) Effect of High-Ratio Stretching

In FIG. 12, Reference Comparative Examples 1 and 2 for thinhigh-performance polarizing films show conventional processes thatinclude subjecting a thin PVA-based resin to dry stretching togetherwith a resin substrate. It is difficult for such conventional processesto make a thin polarizing film having the optical properties of a singletransmittance of 42.0% or more and a polarization rate of 99.95% ormore. This is because of the use of a stretching method called “drystretching”. It is difficult for dry stretching to achieve stretching ata temperature lower than the glass transition temperature of the resinsubstrate to be stretched. It usually leads to breaking of the resinsubstrate being stretched. Even if the resin substrate was stretched, itwould not be uniformly stretched. Thus, dry stretching is usuallyperformed at a temperature higher than the glass transition temperatureof the resin substrate to be stretched. To perform stretching at a lowtemperature of 65° C. or less, it is necessary to select a resinsubstrate with a glass transition temperature of 65° C. or less as theobject to be stretched.

The relationship between the glass transition temperature and thestretching temperature also applies to the PVA-type resin layer. Acommon PVA-based resin has a glass transition temperature of about 80°C., and it is difficult for dry stretching to achieve uniform,high-ratio stretching at a temperature lower than the glass transitiontemperature. In addition, if dry stretching is performed regardless oftemperature, the PVA-based resin will be crystallized by the stretching,which makes it difficult to stretch the object including the resinsubstrate to a total stretch ratio of 5 times or more the originallength. It is also conceivable that a higher order structure (largerstructure) non-contributable to the orientation, such as a lamellarstructure or a spherulite, is formed in the PVA-based resin, so that adichroic material cannot be sufficiently adsorbed or highly oriented.These seem to be the reason why thin polarizing films obtained byconventional processes have a low level of optical properties.

A discussion is given of the method shown in FIG. 12 for producing athin high-performance polarizing film. For example, a thin PVA-basedresin formed on a resin substrate is stretched in an aqueous boric acidsolution at 65° C. or less. The resin substrate is a composition havinga glass transition temperature of 65° C. or more, preferably, a resinsubstrate made of an amorphous ester- or olefin-based thermoplasticresin. Thanks to the function of water molecules as a plasticizer, theresin substrate can be stretched even at 65° C. or less even when it hasa glass transition temperature of 65° C. or more. Water molecules alsofunction as a plasticizer for the PVA-based resin. Thus, the thinPVA-based resin can be stretched together with the resin substrate in anaqueous boric acid solution at 65° C. or less.

This makes it possible to stretch the thin PVA-based resin to a highratio of 5 times or more while crystallization of the PVA-based resin isprevented. It is thus concluded that the amorphous part of the thinPVA-based resin can be highly oriented. The high-ratio stretching alsomakes it possible to align a dichroic material in the PVA-based resin,such as a polyiodide ion complex, highly in a single direction. As aresult, a thin polarizing film with a high level of optical properties,what is called a thin high-performance polarizing film, is obtained.

Embodiments of the thin high-performance polarizing film are describedbelow.

A first embodiment is directed to a thin high-performance polarizingfilm with a thickness of 7 μm or less, which is formed integrally with aresin substrate, made of a PVA-based resin containing an orienteddichroic material, and has the optical properties of a singletransmittance of 42.0% or more and a polarization rate of 99.95% ormore. Refer to the table of FIG. 13. This shows successful developmentof thin high-performance polarizing films that make it possible to formthinner displays, to eliminate display unevenness, and to reduce energyconsumption, and have optical properties close to the ideal propertiesshown in the T-P graph of FIG. 16, which have been considered to bedifficult to achieve. The optical properties are comparable to thoseachieved by thick polarizing films.

In the first embodiment, the resin substrate is made of an ester- orolefin-based thermoplastic resin having a water absorption of 0.50% ormore and a glass transition temperature in the range of 25° C. to 85° C.Specifically, the resin substrate is an ester-based resin film such asan amorphous polyethylene terephthalate film (A-PET film). The resinsubstrate is preferably made of a transparent resin when it is used asan optically functional film to protect one side of the thinhigh-performance polarizing film. The dichroic material adsorbed to andoriented in the thin high-performance polarizing film may be any ofiodine, an organic dye, or a mixture thereof.

A second embodiment is directed to a method for producing, on a resinsubstrate, a thin high-performance polarizing film with a thickness of 7μm or less made of a PVA-based resin containing an oriented dichroicmaterial, and having the optical properties of a single transmittance of42.0% or more and a polarization rate of 99.95% or more. Specifically,the manufacturing method first includes the processes of applying aPVA-based resin aqueous solution to a resin substrate with a thicknessof at least 20 μm and drying the applied solution to form a PVA-typeresin layer. Also in the second embodiment, the resin substrate is madeof an ester- or olefin-based thermoplastic resin having a waterabsorption of 0.50% or more and a glass transition temperature in therange of 25° C. to 85° C. as in the first embodiment. The resinsubstrate is preferably made of a transparent resin when it is used asan optically functional film to protect one side of the thinhigh-performance polarizing film.

The manufacturing method then includes the process of immersing theformed PVA-type resin layer in a dyeing solution containing a dichroicmaterial to adsorb the dichroic material to the PVA-type resin layer. Asin the first embodiment, the dichroic material may be any of iodine, anorganic dye, or a mixture thereof. In the dyeing solution, the dichroicmaterial at 0.1 wt % to 4.5 wt % in the aqueous solution is adsorbedinto the PVA-type resin layer by immersion for 5 to 60 seconds. Wheniodine is used as the dichroic material, it is more preferred that aniodide should be further added to the solution, so that the dissolutionof iodine can be enhanced and the dyeing efficiency can be furtherincreased.

The effect of the elution of the hydrophilic PVA-based resin into theaqueous solution in the dyeing process is a non-negligible technicalproblem in the production of a thin polarizing film, while it isnegligible in the production of a thick polarizing film. It is importantto prevent the PVA-based resin from being eluted into the aqueoussolution during the dyeing. If the dyeing process is performed in ashort time, the elution will be negligible. In some cases, however, theelution can also affect the finished quality of the polarizing film. Itis effective to previously subject the PVA-type resin layer to aninsolubilization treatment before the PVA-type resin layer formed on theresin substrate is immersed in the dyeing solution. A method ofimmersing the PVA-type resin layer in an aqueous boric acid solution atroom temperature enables the insolubilization of the PVA-type resinlayer.

The manufacturing method further includes the process of stretching thePVA-type resin layer, which contains the adsorbed dichroic material,together with the resin substrate in an aqueous boric acid solution. Ifthe PVA-type resin layer is eluted into an aqueous solution anddecreases in thickness during stretching, it will be difficult tostretch the PVA-type resin layer to a total stretch ratio of 5 times ormore, namely, to stretch the PVA-type resin layer to 5 times or more itsoriginal length. However, high-ratio stretching of the PVA-type resinlayer containing an adsorbed dichroic material is achieved in an aqueousboric acid solution, where effective crosslinking with boric acid andinsolubilization are possible at the same time, so that the performanceof the orientation is successfully increased.

As already pointed out, “dry stretching” cannot achieve a total stretchratio of 5 times or more the original length in the production of a thinpolarizing film. In order to prevent crystallization of the PVA-typeresin layer during the stretching, it is preferred that a resinsubstrate capable of being stretched to a high ratio even at atemperature lower than the glass transition temperature of the resinsubstrate should be selected for the use of an aqueous boric acidsolution at a low temperature of 65° C. or less.

As shown in the table of FIG. 13, a thin high-performance polarizingfilm with a thickness of 7 μm or less made of a PVA-based resincontaining an oriented dichroic material, and having the opticalproperties of a single transmittance of 42.0% or more and a polarizationrate of 99.95% or more can be produced on a resin substrate throughthese processes.

Another resin film may be placed on the other side of the resinsubstrate, opposite to its side where the thin high-performancepolarizing film is formed integrally with the resin substrate, with anadhesive interposed therebetween, and the thin high-performancepolarizing film may be transferred to the other resin film by peelingoff it from the resin substrate. An optically functional film may beused as the resin film for the transfer, so that the opticallyfunctional film can be provided on one side of the produced thinhigh-performance polarizing film. A second optically functional film mayalso be placed on the other side of the thin high-performance polarizingfilm, opposite to the side where the optically functional film has beenformed, with an adhesive interposed therebetween. Thus, the producedthin high-performance polarizing film has both sides covered with theoptically functional films.

A third embodiment is directed to a method for producing a laminate filmincluding a thin high-performance polarizing film containing an orienteddichroic material. More specifically, the third embodiment is directedto a method for producing a laminate film including a resin substrateand a thin high-performance polarizing film with a thickness of 7 μm orless formed on one side of the resin substrate, made of a PVA-type resinlayer containing an oriented dichroic material, and having the opticalproperties of a single transmittance of 42.0% or more and a polarizationrate of 99.95% or more, which includes the processes described below.

The manufacturing method includes the manufacturing process of alaminate film including a resin substrate with a thickness of at least20 μm and a PVA-type resin layer formed by applying a PVA-basedresin-containing aqueous solution to one side of the resin substrate anddrying the applied solution. Also in the third embodiment, the resinsubstrate is made of an ester- or olefin-based thermoplastic resinhaving a water absorption of 0.50% or more and a glass transitiontemperature in the range of 25° C. to 85° C. as in the first and thesecond embodiments. The resin substrate is preferably made of atransparent resin when it is used as an optically functional film toprotect one side of the thin high-performance polarizing film.

The manufacturing method includes the process of immersing the laminatefilm, which includes the resin substrate and the PVA-type resin layerformed on one side of the resin substrate, in a dyeing solutioncontaining a dichroic material to adsorb the dichroic material to thePVA-type resin layer of the laminate film. As in the first and secondembodiments, the dichroic material may be any of iodine, an organic dye,or a mixture thereof. In the dyeing solution, the dichroic material at0.1 wt % to 4.5 wt % in the aqueous solution is adsorbed into thePVA-type resin layer by immersion for 5 to 60 seconds as in the secondembodiment. When iodine is used as the dichroic material, it is morepreferred that an iodide should be further added to the solution, sothat the dissolution of iodine can be enhanced and the dyeing efficiencycan be further increased. It is more preferred that before the PVA-typeresin layer of the laminate film is immersed in the dyeing solutioncontaining a dichroic material, the PVA-type resin layer should beinsolubilized by immersing the laminate film in an aqueous boric acidsolution at room temperature in advance.

The manufacturing method further includes the process of stretching thelaminate film, which has the PVA-type resin layer containing theadsorbed dichroic material, in an aqueous boric acid solution. Aspointed out with respect to the second embodiment, if the PVA-type resinlayer is eluted into an aqueous solution and decreases in thicknesstogether with the resin substrate during stretching, it will bedifficult to stretch the PVA-type resin layer of the laminate film to atotal stretch ratio of 5 times or more, namely, to stretch the PVA-typeresin layer to 5 times or more its original length. However, high-ratiostretching of the PVA-type resin layer, which is formed integrally withthe resin substrate and contains the adsorbed dichroic material, isachieved in an aqueous boric acid solution, where effective crosslinkingwith boric acid and insolubilization are possible at the same time, sothat the performance of the orientation of the dichroic material issuccessfully increased.

In order to prevent crystallization of the PVA-type resin layer duringthe stretching of the laminate film, it is preferred that a resinsubstrate capable of being stretched to a high ratio even at atemperature lower than the glass transition temperature of the resinsubstrate of the laminate film should be selected for the stretching ofthe laminate film in an aqueous boric acid solution at a low temperatureof 65° C. or less.

As shown in the table of FIG. 13, a laminate film including a resinsubstrate and a thin high-performance polarizing film with a thicknessof 7 μm or less formed on one side of the resin substrate, made of aPVA-type resin layer containing an oriented dichroic material, andhaving the optical properties of a single transmittance of 42.0% or moreand a polarization rate of 99.95% or more is produced through theseprocesses.

The manufacturing method may include the process of cleaning theproduced laminate film, which has the thin high-performance polarizingfilm made of the PVA-based resin containing the oriented dichroicmaterial, with an iodide salt-containing aqueous solution at atemperature lower than the glass transition temperature of the resinsubstrate of the laminate film. The manufacturing method may furtherinclude the process of drying the cleaned laminate film at a temperatureof 50° C. to 100° C.

The manufacturing method may further include the process of placing anoptically functional film on the other side of the thin high-performancepolarizing film, which is formed on one side of the resin substrate filmin the dried laminate film, with an adhesive interposed therebetween, sothat the produced thin high-performance polarizing film has both sidescovered with the optically functional films. Alternatively, anotherresin film may be placed on the other side of the resin substrate of thedried laminate film, opposite to its side where the thinhigh-performance polarizing film is formed, with an adhesive interposedtherebetween, and the thin high-performance polarizing film may betransferred to the other resin film by peeling off it from the resinsubstrate, so that the produced thin high-performance polarizing filmhas one side covered with an optically functional film made of the resinfilm used for the transfer.

[Outline of the Process of Producing Thin High-Performance PolarizingFilm]

The production of the thin high-performance polarizing film 10 isdescribed on the basis of Reference Production Example 1. As shown inFIG. 11, for example, the resin substrate 11 used is an amorphouspolyethylene terephthalate film with a glass transition temperature of80° C. The resin substrate 11 can support one side of the thinhigh-performance polarizing film 10. Before stretched, the resinsubstrate 11 may preferably have a thickness in the range of 20 μm to500 μm. The resin substrate 11 may be made of a hydrophobic resinnon-swellable and insoluble in water so that it can be prevented frombeing dyed with a dichroic material 14′. Specifically, such a resin doesnot have a dissociable group such as a carboxyl, sulfonic acid, orquaternary amino group, or a nonionic hydrophilic group such as ahydroxyl or amide group.

The resin substrate 11 is typically an ester-based resin film or anolefin-based resin film, preferably an amorphous polyethyleneterephthalate film. A crystallized polyethylene terephthalate film,which usually has a high elastic modulus, is difficult to stretch at lowtemperature. In contrast, an amorphous polyethylene terephthalate filmcan be stretched even at low temperature. The surface of the resinsubstrate may be subjected to a surface modificating treatment such as acorona treatment so that it can have improved adhesion to the PVA-typeresin layer 12. An adhesive layer may also be provided. The resinsubstrate 11 preferably has a water absorption (JIS K 7209) of 0.3% ormore, and more preferably 0.5% or more. The resin substrate preferablyhas a glass transition temperature (JIS K 7121, DSC method) of 85° C. orless, and more preferably 25° C. to 85° C. A resin film with suchphysical properties can be stretched to a high ratio even in an aqueousboric acid solution at 65° C. or less.

A laminate film 13 including the resin substrate 11 and the PVA-typeresin layer 12 is produced by a process (A).

In the producing process (A), a film roll is first provided, whichincludes the resin substrate 11 with a thickness of 100 μm. An aqueoussolution containing 3 to 10 parts by weight of a PVA-based resin and 100parts by weight of a solvent is then provided. The resin substrate 11 isdrawn from the provided film roll, and the aqueous solution of thePVA-based resin is applied to the resin substrate. A PVA-type resinlayer 12 with a thickness of 10 μm is formed on the resin substrate 11by drying in an oven at 60° C. The resulting laminate film 13 in theform of a continuous web may be wound into a roll. The laminate film 13is then processed by a series of processes as described below.

First, a dyeing process (B) is performed. This process includesimmersing the laminate film 13 in a dyeing solution 14 to adsorb adichroic material 14′ to the PVA-type resin layer 12. Water is usuallyused as the solvent in the dyeing solution 14. The dichroic material 14′is generally used in an amount of 0.1 to 4.3 parts by weight (0.1 to 4.5wt %) based on 100 parts by weight of the solvent composed mainly ofwater. For example, the dichroic material 14′ may be iodine, an organicdye, or a mixture thereof. These dichroic materials may be used alone orin combination of two or more.

When iodine is used as the dichroic material 14′, it is preferred thatan iodide should be further added to the solution, so that thedissolution of iodine can be enhanced and the dyeing efficiency can befurther increased. Based on 100 parts by weight of the solvent, theiodide is preferably used in an amount of 0.02 to 20 parts by weight,and more preferably 0.1 to 10 parts by weight. Examples of the iodideinclude potassium iodide, lithium iodide, sodium iodide, zinc iodide,aluminum iodide, lead iodide, copper iodide, barium iodide, calciumiodide, tin iodide, titanium iodide, etc. In particular, potassiumiodide is preferably added. The immersion time in the dyeing solution 14is generally, but not limited to, about 5 seconds to about 5 minutes.The temperature of the dyeing solution 14 is generally from about 20 toabout 50° C.

In the dyeing process (B), the laminate film 13 was immersed in thedyeing solution 14 containing iodine and potassium iodide at atemperature of 30° C. for 30 seconds. In this process, iodide wasadsorbed to the PVA-type resin layer 12. The dyeing solution 14contained 0.1 parts by weight of iodine, 0.7 parts by weight ofpotassium iodide, and 100 parts by weight of water.

Subsequently, a crosslinking process (C) is performed together with astretching process (D). The crosslinking process (C) includes immersingthe laminate film 13 in an aqueous boric acid solution 15 to crosslinkthe PVA-type resin layer 12 containing the adsorbed dichroic material14′. The crosslinking process (C) also serves as an insolubilizationprocess in which the swelling PVA-based resin is made insoluble inwater.

The aqueous boric acid solution 15 is obtained by dissolving boric acidor a borate in water as a solvent. Besides boric acid or a borate, aboron compound such as borax, glyoxal, glutaraldehyde, or the like maybe used. In general, 1 to 10 parts by weight of boric acid is used basedon 100 parts by weight of water. An iodide for suppressing elution ofiodine adsorbed to the PVA-type resin layer 12 is preferably added tothe aqueous boric acid solution 15. The concentration of the iodide ispreferably from 0.05 to 15% by weight, more preferably from 0.5 to 8% byweight. Examples of the iodide are the same as those in the case of thedyeing process (A). The immersion time in the aqueous boric acidsolution 16 is generally, but not limited to, about 15 seconds to about5 minutes. The temperature of the aqueous boric acid solution 15 isgenerally from about 20 to about 70° C.

The PVA-type resin layer 12 containing the adsorbed iodine was stretchedtogether with the resin substrate 11 by means of a roll type stretchingapparatus 16 having a plurality of sets of rollers different incircumferential speed, while it was crosslinked in the aqueous boricacid solution 15 containing potassium iodide at a temperature of 60° C.Thus, the crosslinking process (C) is performed together with thestretching process (D). In the stretching process (D), the laminate film13 was longitudinally and uniaxially stretched to a stretch ratio of 5.0times. In this process, the aqueous boric acid solution 15 contained 4parts by weight of boric acid, 5 parts by weight of potassium iodide,and 100 parts by weight of water.

The temperature of the aqueous boric acid solution 15 is preferably 85°C. or less. If it is more than 85° C., elution of iodine adsorbed to thePVA-based resin can be facilitated, and the PVA-based resin can also beeluted, so that the produced thin high-performance polarizing film 10may have degraded optical properties. In addition, if the PVA-type resinlayer 12 is thin, the PVA-type resin layer 12 can be dissolved, so thatthe optical properties of the resulting thin high-performance polarizingfilm 10 may be further degraded. The temperature of the aqueous boricacid solution is more preferably from 30° C. to 65° C. If thetemperature of the aqueous boric acid solution 15 is less than 30° C.,water cannot sufficiently function as a plasticizer, so that the resinsubstrate 11 and the PVA-type resin layer 12 cannot be sufficientlysoftened, which makes it difficult to stretch the laminate film 13 to atotal stretch ratio of 5 times or more its original length.

In the aqueous boric acid solution 15, the laminate film 13 ispreferably stretched to a stretch ratio of 5 times or more, morepreferably 5.5 times or more its original length. If the stretch ratiois less than 5 times, the dichroic material 14′ cannot be sufficientlyoriented, so that the resulting thin high-performance polarizing film 10can have degraded optical properties. If the stretch ratio is more than6.5 times, the laminate film 13 will be more likely to rupture, whichmakes stable production difficult. When single-step stretching isperformed, the term “stretch ratio” refers to the stretch ratio in thesingle-step stretching procedure. When multi-step stretching isperformed using a plurality of stretching machines placed in an aqueoussolution, the term “stretch ratio” refers to the total of stretch ratios(the total stretch ratio) in the respective steps.

As shown in FIG. 11, the crosslinking process using the aqueous boricacid solution may be performed before the dyeing process (B). In theproduction of a thick polarizing film, this crosslinking process (E) isunnecessary because elution of PVA-based resin is negligible. However,elution of PVA-based resin into the dyeing solution 14 is not negligiblein the production of the thin high-performance polarizing film 10 usingthe laminate film 13 including the resin substrate 11 and the thin PVAresin layer 12 formed thereon. Thus, performing the crosslinking process(E) before the dyeing process (B) is effective in the production of athin high-performance polarizing film with a high level of opticalproperties. A separate crosslinking process (F) using an aqueous boricacid solution may also be performed before the stretching process (D) inthe aqueous boric acid solution so that boric acid released during thedyeing process can be supplemented.

After stretched to 5.0 times, the laminate film 13 was taken out of theaqueous boric acid solution 15 and then fed to a cleaning process (G).The cleaning process (G) includes cleaning away unnecessary residuesfrom the laminate film including the thin high-performance polarizingfilm 10 having undergone various treatments. If this treatment isinsufficient, boric acid may precipitate from the thin high-performancepolarizing film 10 after the drying of the laminate film. The cleaningmay be performed in a cleaning liquid containing potassium iodide sothat the PVA resin can be prevented from being dissolved. Theconcentration of potassium iodide in the cleaning liquid is from about0.5 to about 10% by weight. The temperature of the cleaning liquid isfrom about 10 to about 50° C. The immersion time is generally from about1 second to about 1 minute.

The final process is a drying process (H). The drying process (H) may beperformed using any appropriate method such as natural drying, drying byblowing, or drying by heating. In Reference Production Example 1, dryingwas performed with heated air at 60° C. for 30 seconds.

In the finished laminate film, the PVA-type resin layer 12 stretchedtogether with the resin substrate 11 had a thickness of 3 μm. The thinhigh-performance polarizing film 10 made of the PVA resin with athickness of 3 μm containing oriented iodine was successfully formed onthe resin substrate 11. This product is the thin high-performancepolarizing film 10 of Reference Production Example 1 whose propertiesare shown in the table of FIG. 13.

The laminate film having the thin high-performance polarizing film 10formed on the resin substrate 11 may be subjected to a transferringprocess (I) as shown in FIG. 11. In the transferring process (I), theresin substrate 11 may be released from the thin high-performancepolarizing film 10, and the thin high-performance polarizing film 10 maybe transferred to any other optically functional film.

The PVA-based resin used to form the thin high-performance polarizingfilm can be obtained by saponifying a polyvinyl acetate-based resin. Thedegree of saponification is generally from 85% by mole to 100% by mole,and the degree of polymerization is generally from 1,000 to 10,000. ThisPVA-based resin is polyvinyl alcohol or an ethylene-vinyl alcoholcopolymer.

The produced thin high-performance polarizing film 10 preferablyexhibits absorption dichroism at any wavelength in the visible lightregion (a wavelength of 380 nm to 780 nm). The produced thinhigh-performance polarizing film 10 has a thickness of 7 μm or less,preferably 0.5 μm to 5 μm. The thin high-performance polarizing film 10has low shrinkage stress and thus has high dimensional stability even ina high-temperature environment, and also exhibits the optical propertiesof a single transmittance of 42.0% or more and a polarization rate of99.95% or more.

Reference Production Example 1 Process of Preparing Laminate

The resin substrate used was an amorphous polyethylene terephthalatefilm (NOVACLEAR manufactured by Mitsubishi Plastics, Inc.) with a glasstransition temperature of 80° C. A laminate film including the resinsubstrate and a polyvinyl alcohol layer was prepared as follows. First,the resin substrate was provided, which had a thickness of 100 μm. Anaqueous solution of polyvinyl alcohol (NH26 manufactured by The NipponSynthetic Chemical Industry Co., Ltd.) was then applied to the resinsubstrate. A 12-μm-thick polyvinyl alcohol layer was formed by dryingthe applied solution at a temperature of 60° C. As a result, a laminatefilm was obtained.

(Insolubilization Process)

The resulting laminate film was immersed in an aqueous boric acidsolution at a temperature of 30° C. for 30 seconds. The aqueous boricacid solution contained 4 parts by weight of boric acid and 100 parts byweight of water.

(Dyeing Process)

The prepared laminate film was immersed in a dyeing solution containingiodine and potassium iodide at a temperature of 30° C. for a desiredperiod of time in such a manner that a polarizing film with a singletransmittance of 40 to 44% could be finally obtained. In this process,iodine was adsorbed to the polyvinyl alcohol layer. The dyeing solutioncontained 0.1 parts by weight of iodine, 0.7 parts by weight ofpotassium iodide, and 100 parts by weight of water.

(Crosslinking Process)

The laminate film was then immersed in an aqueous boric acid solutioncontaining boric acid and potassium iodide at a temperature of 30° C.for 30 seconds. The aqueous boric acid solution contained 3 parts byweight of boric acid, 3 parts by weight of potassium iodide, and 100parts by weight of water.

In an aqueous boric acid solution containing boric acid and potassiumiodide at a temperature of 60° C., the laminate film including the resinsubstrate and the polyvinyl alcohol layer containing the adsorbed iodinewas longitudinally and uniaxially stretched to an extent just beforebreaking point by allowing it to pass through a plurality of sets ofrollers different in circumferential speed. In this process, the stretchratio (maximum stretch ratio) was 5.0 times. The aqueous boric acidsolution contained 4 parts by weigh of boric acid, 5 parts by weight ofpotassium iodide, and 100 parts by weight of water. For this process,the phrases “just before breaking point” and the “maximum stretch ratio”were determined after the breaking stretch ratio was determined inadvance. More specifically, the phrases refer to a stretch ratio about0.2 (times) lower than the breaking stretch ratio determined in advance.

(Cleaning Process)

Subsequently, the laminate film was immersed in an aqueous potassiumiodide solution at a temperature of 30° C. for 30 seconds so that theboric acid deposited on the surface was washed off. The aqueouspotassium iodide solution contained 3 parts by weight of potassiumiodide and 100 parts by weigh of water.

The laminate film, which had been stretched to 5.0 times, was taken outof the aqueous boric acid solution and then dried with heated air at 60°C. The polyvinyl alcohol layer stretched together with the resinsubstrate had a thickness of 5 μm. Thus, a 5-μm-thick polyvinyl alcoholresin layer containing oriented iodine was obtained on the resinsubstrate. The product is the thin high-performance polarizing film ofReference Production Example 1 whose properties are shown in the tableof FIG. 13.

Reference Production Example 2

The resin substrate used was a polymethylpentene film (TPX manufacturedby Mitsui Chemicals, Inc.) with a glass transition temperature of 30° C.Using a process similar to that of Reference Production Example 1,Reference Production Example 2 was performed in which a laminate filmincluding the resin substrate and a polyvinyl alcohol layer (7 μm inthickness) containing adsorbed iodine was longitudinally and uniaxiallystretched to an extent just before breaking point by allowing it to passthrough a plurality of sets of rollers different in circumferentialspeed in an aqueous boric acid solution containing boric acid andpotassium iodide at a temperature of 60° C. In this process, the stretchratio (maximum stretch ratio) was 5.5 times.

As used herein, the phrases “just before breaking point” and the“maximum stretch ratio” mean a stretch ratio about 0.2 (times) lowerthan the breaking stretch ratio determined in advance as in the case ofReference Production Example 1. As a result, a 3-μm-thick polyvinylalcohol resin layer containing oriented iodine was obtained on the resinsubstrate. The product is the thin high-performance polarizing film ofReference Production Example 2 whose properties are shown in the tableof FIG. 13.

Reference Comparative Example 1

The resin substrate used was an amorphous polyethylene terephthalatefilm (NOVACLEAR manufactured by Mitsubishi Plastics, Inc.) with a glasstransition temperature of 80° C. A laminate film including the resinsubstrate with a thickness of 100 μm and a polyvinyl alcohol resin layerwith a thickness of 10 μm formed thereon was prepared using the sameprocess as in Reference Production Example 1. Subsequently, the laminatefilm was longitudinally and uniaxially stretched to an extent justbefore breaking point in an oven at 110° C. In this process, the stretchratio (maximum stretch ratio) was 4.0 times. As used herein, the phrases“just before breaking point” and the “maximum stretch ratio” mean astretch ratio about 0.2 (times) lower than the breaking stretch ratiodetermined in advance as in the case of Reference Production Example 1.

The stretched laminate film was further immersed in a dyeing solution asin Reference Production Example 1 for a desired period of time in such amanner that a polarizing film with a transmittance of 40 to 44% could befinally obtained. The laminate film taken out of the dyeing solution wasdried with heated air at 60° C. The polyvinyl alcohol resin layerstretched together with the resin substrate had a thickness of 4 μm.Thus, a 4-μm-thick polyvinyl alcohol resin layer containing orientediodine was obtained on the resin substrate. The product is the thinpolarizing film of Reference Comparative Example 1 whose properties areshown in the table of FIG. 13.

Reference Comparative Example 2

A laminate film including a 100-μm-thick resin substrate and a10-μm-thick polyvinyl alcohol resin layer formed thereon was prepared asin Reference Production Example 1. The prepared laminate film wasimmersed in a dyeing solution as in Reference Production Example 1 for adesired period of time in such a manner that a polarizing film with atransmittance of 40 to 44% could be finally obtained. The laminate filmtaken out of the dyeing solution was dried with heated air at 60° C. Thelaminate film containing the adsorbed iodine was longitudinally anduniaxially stretched to an extent just before breaking point in an ovenat 90° C. In this process, the stretch ratio (maximum stretch ratio) was4.5 times. As used herein, the “just before breaking point” and the“maximum stretch ratio” mean a stretch ratio about 0.2 (times) lowerthan the breaking stretch ratio determined in advance as in the case ofReference Production Example 1.

The polyvinyl alcohol layer stretched together with the resin substratehad a thickness of 4 μm. Thus, a 4-μm-thick polyvinyl alcohol resinlayer containing oriented iodine was obtained on the resin substrate.The product is the thin polarizing film of Reference Comparative Example2 whose properties are shown in the table of FIG. 13.

[Measurement Methods] [Measurement of Thickness]

The thickness of the resin substrate and the thin polarizing film wasmeasured using a digital micrometer (KC-351C manufactured by ANRITSUCORPORATION).

[Measurement of Transmittance and Polarization Rate]

The single transmittance T, parallel transmittance Tp, and crosstransmittance Tc of the thin polarizing film were measured using anultraviolet-visible spectrometer (V7100 manufactured by JASCOCorporation). The transmittances T, Tp, and Tc are Y values which haveundergone luminosity correction in the two-degree visual field (Cilluminant) according to JIS Z 8701.

The degree P of polarization was calculated from the following formula,using the transmittances.

Degree P (%) of polarization={(Tp−Tc)/(Tp+Tc)}^(1/2)×100

The contrast ratio (CR) of the polarizing film was calculated from thefollowing formula.

CR=Tp/Tc

The contrast ratio (CR) of the display was calculated from the followingformula.

CR=maximum brightness/minimum brightness

The thin polarizing film disclosed in the specification of JapanesePatent Application No. 2010-269002 or the specification of JapanesePatent Application No. 2010-263692 is a polarizing film in the form of acontinuous web including a PVA-based resin containing an orienteddichroic material, which is made with a thickness of 10 μm or less by atwo-stage stretching process including auxiliary in-air stretching of alaminate and stretching of the laminate in an aqueous boric acidsolution, wherein the laminate includes an amorphous ester-basedthermoplastic resin substrate and a PVA-type resin layer formed thereon.This thin polarizing film is preferably made to have optical propertiessatisfying the following requirements: P>−(10^(0.929T-42.4)−1)×100(provided that T<42.3) and P≧99.9 (provided that T≧42.3), wherein Trepresents the single transmittance, and P represents the polarizationrate.

Specifically, the thin polarizing film can be produced by a thinpolarizing film-manufacturing method including the processes of:performing elevated temperature in-air stretching of a PVA-type resinlayer, so that a stretched intermediate product including an orientedPVA-type resin layer is produced, wherein the PVA-type resin layer isformed on an amorphous ester-based thermoplastic resin substrate in theform of a continuous web; absorbing a dichroic material (which ispreferably iodine or a mixture of iodine and an organic dye) to thestretched intermediate product to produce a colored intermediate productincluding the PVA-type resin layer in which the dichroic material isoriented; and performing stretching of the colored intermediate productin an aqueous boric acid solution so that a polarizing film with athickness of 10 μm or less is produced, which includes the PVA-typeresin layer containing the oriented dichroic material.

In this manufacturing method, the elevated temperature in-air stretchingand the stretching in an aqueous boric acid solution are preferablyperformed in such a manner that the PVA-type resin layer formed on theamorphous ester-based thermoplastic resin substrate is stretched to atotal stretch ratio of 5 times or more. The aqueous boric acid solutionpreferably has a temperature of 60° C. or more for the stretchingtherein. Before stretched in the aqueous boric acid solution, thecolored intermediate product is preferably subjected to aninsolubilization treatment, in which the colored intermediate product ispreferably immersed in an aqueous boric acid solution with a temperatureof 40° C. or less. The amorphous ester-based thermoplastic resinsubstrate may be made of amorphous polyethylene terephthalate includingco-polyethylene terephthalate in which isophthalic acid,cyclohexanedimethanol, or any other monomer is copolymerized, and ispreferably made of a transparent resin. The thickness of the substratemay be at least seven times the thickness of the PVA-type resin layer tobe formed. The elevated temperature in-air stretching is preferablyperformed at a stretch ratio of 3.5 times or less, and the temperatureof the elevated temperature in-air stretching is preferably equal to orhigher than the glass transition temperature of the PVA-based resin.Specifically, it is preferably in the range of 95° C. to 150° C. Whenthe elevated temperature in-air stretching is end-free uniaxialstretching, the PVA-type resin layer formed on the amorphous ester-basedthermoplastic resin substrate is preferably stretched to a total stretchratio of from 5 to 7.5 times. When the elevated temperature in-airstretching is fixed-end uniaxial stretching, the PVA-type resin layerformed on the amorphous ester-based thermoplastic resin substrate ispreferably stretched to a total stretch ratio of from 5 to 8.5 times.

More specifically, the thin polarizing film can be produced by themethod described below.

A substrate in the form of a continuous web is prepared, which is madeof co-polymerized polyethylene terephthalate (amorphous PET) in which 6mol % of isophthalic acid is copolymerized. The amorphous PET has aglass transition temperature of 75° C. A laminate of a polyvinyl alcohol(PVA) layer and the amorphous PET substrate in the form of a continuousweb is prepared as described below. Incidentally, the glass transitiontemperature of PVA is 80° C.

A 200 μm thick amorphous PET substrate is provided, and an aqueous 4-5%PVA solution is prepared by dissolving PVA powder with a polymerizationdegree of 1,000 or more and a saponification degree of 99% or more inwater. Subsequently, the aqueous PVA solution is applied to a 200 μmthick amorphous PET substrate and dried at a temperature of 50 to 60° C.so that a laminate composed of the amorphous PET substrate and a 7 μmthick PVA layer formed thereon is obtained.

The laminate having the 7 μm thick PVA layer is subjected to a two-stagestretching process including auxiliary in-air stretching and stretchingin an aqueous boric acid solution as described below, so that a thinhigh-performance polarizing film with a thickness of 3 μm is obtained.At the first stage, the laminate having the 7 μm thick PVA layer issubjected to an auxiliary in-air stretching process so that the layer isstretched together with the amorphous PET substrate to form a stretchedlaminate having a 5 μm thick PVA layer. Specifically, the stretchedlaminate is formed by a process including feeding the laminate havingthe 7 μm thick PVA layer to a stretching apparatus placed in an ovenwith the stretching temperature environment set at 130° C. andsubjecting the laminate to end-free uniaxial stretching to a stretchratio of 1.8 times. In the stretched laminate, the PVA layer ismodified, by the stretching, into a 5 μm thick PVA layer containingoriented PVA molecules.

Subsequently, a dyeing process is performed to produce a coloredlaminate having a 5 μm thick PVA layer containing oriented PVA moleculesand absorbed iodine. Specifically, the colored laminate is produced byimmersing the stretched laminate for a certain time period in a dyeingliquid containing iodine and potassium iodide and having a temperatureof 30° C. so that iodine can be absorbed to the PVA layer of thestretched laminate and that the PVA layer for finally forming ahighly-functional polarizing film can have a single transmittance of 40to 44%. In this process, the dyeing liquid contains water as a solventand has an iodine concentration in the range of 0.12 to 0.30% by weightand a potassium iodide concentration in the range of 0.7 to 2.1% byweight. The concentration ratio of iodine to potassium iodide is 1:7. Itshould be noted that potassium iodide is necessary to make iodinesoluble in water. More specifically, the stretched laminate is immersedfor 60 seconds in a dyeing liquid containing 0.30% by weight of iodineand 2.1% by weight of potassium iodide, so that a colored laminate isproduced, in which the 5 μm thick PVA layer contains oriented PVAmolecules and absorbed iodine.

At the second stage, the colored laminate is further subjected to astretching process in an aqueous boric acid so that the layer is furtherstretched together with the amorphous PET substrate to form an opticalfilm laminate having a 3 μm thick PVA layer, which forms ahighly-functional polarizing film. Specifically, the optical filmlaminate is formed by a process including feeding the colored laminateto a stretching apparatus placed in a treatment system in which anaqueous boric acid solution containing boric acid and potassium iodideis set in the temperature range of 60 to 85° C. and subjecting thelaminate to end-free uniaxial stretching to a stretch ratio of 3.3times. More specifically, the aqueous boric acid solution has atemperature of 65° C. In the solution, the boric acid content and thepotassium iodide content are 4 parts by weight and 5 parts by weight,respectively, based on 100 parts by weight of water. In this process,the colored laminate having a controlled amount of absorbed iodine isfirst immersed in the aqueous boric acid solution for 5 to 10 seconds.Subsequently, the colored laminate is directly fed between a pluralityof pairs of rolls different in peripheral speed, which form thestretching apparatus placed in the treatment system, and subjected toend-free uniaxial stretching for 30 to 90 seconds to a stretch ratio of3.3 times. This stretching treatment converts the PVA layer of thecolored laminate to a 3 μm thick PVA layer in which the absorbed iodineforms a polyiodide ion complex highly oriented in a single direction.This PVA layer forms a highly-functional polarizing film in the opticalfilm laminate.

A cleaning process, which is however not essential for the manufactureof the optical film laminate, is preferably performed, in which theoptical film laminate is taken out of the aqueous boric acid solution,and boric acid deposited on the surface of the 3 μm thick PVA layerformed on the amorphous PET substrate is washed off with an aqueouspotassium iodide solution. Subsequently, the cleaned optical filmlaminate is dried in a drying process using warm air at 60° C. It shouldbe noted that the cleaning process is to prevent appearance defects suchas boric acid precipitation.

A lamination and/or transfer process, which is also not essential forthe manufacture of the optical film laminate, may also be performed, inwhich an 80 μm thick triacetylcellulose film is laminated to the surfaceof the 3 μm thick PVA layer formed on the amorphous PET substrate, whilean adhesive is applied to the surface, and then the amorphous PETsubstrate is peeled off, so that the 3 μm thick PVA layer is transferredto the 80 μm thick triacetylcellulose film.

[Other Processes]

The thin polarizing film-manufacturing method may include additionalprocesses other than the above processes. For example, additionalprocesses may include an insolubilization process, a crosslinkingprocess, a drying process (moisture control), etc. Additional processesmay be performed at any appropriate timing.

The insolubilization process is typically achieved by immersing thePVA-type resin layer in an aqueous boric acid solution. Theinsolubilization treatment can impart water resistance to the PVA-typeresin layer. The concentration of boric acid in the aqueous boric acidsolution is preferably from 1 to 4 parts by weight based on 100 parts byweight of water. The insolubilization bath (aqueous boric acid solution)preferably has a temperature of 20° C. to 50° C. Preferably, theinsolubilization process is performed after the preparation of thelaminate and before the dyeing process or the process of stretching inwater.

The crosslinking process is typically achieved by immersing the PVA-typeresin layer in an aqueous boric acid solution. The crosslinkingtreatment can impart water resistance to the PVA-type resin layer. Theconcentration of boric acid in the aqueous boric acid solution ispreferably from 1 to 4 parts by weight based on 100 parts by weight ofwater. When the crosslinking process is performed after the dyeingprocess, an iodide is preferably added to the solution. The addition ofan iodide can suppress the elution of absorbed iodine from the PVA-typeresin layer. The amount of the addition of an iodide is preferably from1 to 5 parts by weight based on 100 parts by weight of water. Examplesof the iodide include those listed above. The temperature of thecrosslinking bath (aqueous boric acid solution) is preferably from 20°C. to 50° C. Preferably, the crosslinking process is performed beforethe second stretching process in the aqueous boric acid solution. In apreferred embodiment, the dyeing process, the crosslinking process, andthe second stretching process in the aqueous boric acid solution areperformed in this order.

A thermoplastic resin with a high level of transparency, mechanicalstrength, thermal stability, moisture blocking properties, isotropy, andthe like may be used as a material for forming the first and secondtransparent protective film. Examples of such a thermoplastic resininclude cellulose resins such as triacetylcellulose, polyester resins,polyethersulfone resins, polysulfone resins, polycarbonate resins,polyamide resins, polyimide resins, polyolefin resins, (meth)acrylicresins, cyclic olefin polymer resins (norbornene resins), polyarylateresins, polystyrene resins, polyvinyl alcohol resins, and any mixturethereof. The transparent protective film is generally laminated to oneside of the polarizer with the adhesive layer, but thermosetting resinsor ultraviolet curing resins such as (meth)acrylic, urethane, acrylicurethane, epoxy, or silicone resins may be used to other side of thepolarizer for the transparent protective film. The transparentprotective film may also contain at least one type of any appropriateadditive. Examples of the additive include an ultraviolet absorbingagent, an antioxidant, a lubricant, a plasticizer, a release agent, ananti-discoloration agent, a flame retardant, a nucleating agent, anantistatic agent, a pigment, and a colorant. The content of thethermoplastic resin in the transparent protective film is preferablyfrom 50 to 100% by weight, more preferably from 50 to 99% by weight,still more preferably from 60 to 98% by weight, particularly preferablyfrom 70 to 97% by weight. If the content of the thermoplastic resin inthe transparent protective film is 50% by weight or less, hightransparency and other properties inherent in the thermoplastic resincan fail to be sufficiently exhibited.

At least one selected from cellulose resins, polycarbonate resins,cyclic polyolefin resins, (meth)acrylic resins and polyester resins ispreferably used for the transparent protective film according to theinvention.

The cellulose resins are an ester of cellulose and a fatty acid.Examples of such a cellulose ester resin include triacetyl cellulose,diacetyl cellulose, tripropionyl cellulose, dipropionyl cellulose, andthe like. In particular, triacetyl cellulose is preferred. Muchcommercially available triacetyl celluloses are placing on sale and areadvantageous in view of easy availability and cost. Examples ofcommercially available products of triacetyl cellulose include UV-50,UV-80, SH-80, TD-80U, TD-TAC, and UZ-TAC (trade names) manufactured byFujifilm Corporation, and KC series manufactured by Konica.

For example, a norbornene resin is preferable in the cyclic polyolefinresins. Cyclic olefin resins are a generic name for resins produced bypolymerization of cyclic olefin used as a polymerizable unit, andexamples thereof include the resins disclosed in JP-A Nos. 01-240517,03-14882, and 03-122137. Specific examples thereof include ring-opened(co)polymers of cyclic olefins, addition polymers of cyclic olefins,copolymers (typically random copolymers) of cyclic olefins and α-olefinssuch as ethylene and propylene, graft polymers produced by modificationthereof with unsaturated carboxylic acids or derivatives thereof, andhydrides thereof. Examples of the cyclic olefin include norbornenemonomers. Various commercially available cyclic polyolefin resins areplacing on sale. Examples thereof include Zeonex (trade name) and Zeonor(trade name) series manufactured by Zeon Corporation, Arton (trade name)series manufactured by JSR Corporation, Topas (trade name) seriesmanufactured by Ticona, and Apel (trade name) series manufactured byMitsui Chemicals, Inc.

Any appropriate (meth)acrylic resins may be used as long as theadvantages of the invention are not reduced. Examples of such a(meth)acrylic resin include poly(meth)acrylate such as poly(methylmethacrylate), methyl methacrylate-(meth)acrylic acid copolymers, methylmethacrylate-(meth)acrylate copolymers, methylmethacrylate-acrylate-(meth)acrylic acid copolymers, methyl(meth)acrylate-styrene copolymers (such as MS resins), and alicyclichydrocarbon group-containing polymers (such as methylmethacrylate-cyclohexyl methacrylate copolymers and methylmethacrylate-norbornyl(meth)acrylate copolymers). Poly(C₁₋₆ alkyl(meth)acrylate) such as poly(methyl (meth)acrylate) is preferred, and amethyl methacrylate-based resin mainly composed of a methyl methacrylateunit (50 to 100% by weight, preferably 70 to 100% by weight) is morepreferred.

Examples of the (meth)acrylic resin include Acrypet VH and AcrypetVRL20A each manufactured by Mitsubishi Rayon Co., Ltd., (meth)acrylicresins having a ring structure in their molecule as disclosed in JP-ANo. 2004-70296, and high-Tg (meth)acrylic resins produced byintramolecular crosslinking or intramolecular cyclization reaction.

Lactone ring structure-containing (meth)acrylic resins may also be used,because they have high heat resistance and high transparency and alsohave high mechanical strength after biaxially stretched. Examples of thelactone ring structure-containing (meth)acrylic reins include thelactone ring structure-containing (meth)acrylic reins disclosed in JP-ANos. 2000-230016, 2001-151814, 2002-120326, 2002-254544, and2005-146084.

Examples of polyester resins include, but are not limited to,homopolymers obtained by polycondensation of one dicarboxylic acid andone diol, copolymers obtained by polycondensation of one or moredicarboxylic acids and two or more diols or copolymers obtained bypolycondensation of two or more dicarboxylic acids and one or morediols, and a resin blend containing two or more of the homopolymers orcopolymers, in which examples of one or more dicarboxylic acids includeterephthalic acid, isophthalic acid, orthophthalic acid,2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid,1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid,diphenylcarboxylic acid, diphenoxyethanedicarboxylic acid,diphenylsulfonecarboxylic acid, anthracenedicarboxylic acid,1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid,1,4-cyclohexanedicarboxylic acid, hexahydroterephthalic acid,hexahydroisophthalic acid, malonic acid, dimethylmalonic acid, succinicacid, 3,3-diethylsuccinic acid, glutaric acid, 2,2-dimethylglutaricacid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelicacid, azelaic acid, dimer acid, sebacic acid, suberic acid, anddodecadicarboxylic acid, and examples of one or more diols includeethylene glycol, propylene glycol, hexamethylene glycol, neopentylglycol, 1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol,decamethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol,1,6-hexanediol, 2,2-bis(4-hydroxyphenyl)propane, andbis(4-hydroxyphenyl)sulfone. In particular, polyethylene terephthalateresins are preferably used. Amorphous polyethylene terephthalate resinsare particularly preferred.

The thickness of the first transparent protective film may be determinedas desired. Generally, in view of strength, workability such ashandleability, thin layer formability, or other properties, thethickness of the first transparent protective film is preferably from 1to 80 μm. The first transparent protective film preferably has athickness of 60 μm or less, more preferably 10 to 60 μm, even morepreferably 10 to 50 μm so that irregularities derived from thepolarizing plate can be kept at a low level.

The first transparent protective film to be used preferably has a hazevalue of 15% or less. A transparent protective film made of any of theabove materials generally has a haze value of 1% or less, preferably0.5% or less, and more preferably 0.3%. Thus, the transparent protectivefilm made of any of the above materials can be used as the firsttransparent protective film without modification.

Alternatively, the first transparent protective film to be used mayinclude a transparent protective film made of any of the above materialsand a hard coating layer or a functional layer for anti-reflection,diffusion, or antiglare purpose, which is provided on a surface of theprotective film opposite to its surface where the polarizer is to bebonded, as long as the first transparent protective film has a hazevalue of 15% or less. When the haze value is 15% or less, a clear,high-grade appearance can be provided. The first transparent protectivefilm having a functional layer also preferably has a low haze value,which is preferably 10% or less, and more preferably 5% or less.

A hard coat processing is applied for the purpose of protecting thesurface of the polarizing plate from damage, and this hard coat film maybe formed by a method in which, for example, a curable coated film withexcellent hardness, slide property etc. is added on the surface of theprotective film using suitable ultraviolet curable type resins, such asacrylic type and silicone type resins. Antireflection processing isapplied for the purpose of antireflection of outdoor daylight on thesurface of a polarizing plate and it may be prepared by forming anantireflection film according to the conventional method etc.

In addition, an anti glare processing is applied in order to prevent adisadvantage that outdoor daylight reflects on the surface of apolarizing plate to disturb visual recognition of transmitting lightthrough the polarizing plate, and the processing may be applied, forexample, by giving a fine concavo-convex structure to a surface of theprotective film using, for example, a suitable method, such as roughsurfacing treatment method by sandblasting or embossing and a method ofcombining transparent fine particle. As a fine particle combined inorder to form a fine concavo-convex structure on the above-mentionedsurface, transparent fine particles whose average particle size is 0.5to 20 μm, for example, such as inorganic type fine particles that mayhave conductivity comprising silica, alumina, titania, zirconia, tinoxides, indium oxides, cadmium oxides, antimony oxides, etc., andorganic type fine particles comprising cross-linked of non-cross-linkedpolymers may be used. When forming fine concavo-convex structure on thesurface, the amount of fine particle used is usually about 2 to 70weight parts to the transparent resin 100 weight parts that forms thefine concavo-convex structure on the surface, and preferably 5 to 50weight parts. An anti glare layer may serve as a diffusion layer(viewing angle expanding function etc.) for diffusing transmitting lightthrough the polarizing plate and expanding a viewing angle etc.

In addition, the above-mentioned functional layer such as antireflectionlayer, diffusion layer and antiglare layer, etc. may be prepared on theprotective film itself, and also they may be prepared as an opticallayer different from the protective film. The functional layer generallyhas a thickness of 10 μm or less, preferably 1 to 10 μm, and morepreferably 3 to 7 μm. The thickness of these functional layers is sodesigned that the first transparent protective film can have a hazevalue of 15% or less, depending on the type or composition of thematerial used to form the functional layer. The first transparentprotective film having the functional layer also preferably has athickness in the above range.

While the first transparent protective film is provided on one side ofthe polarizer, a second transparent protective film may be provided onthe other side of the polarizer. In this case, the first and secondtransparent protective films may be made of the same polymer material ordifferent polymer materials.

The thickness of the second transparent protective film may bedetermined as desired. Generally, in view of strength, workability suchas handleability, thin layer formability, or other properties, thethickness of the second transparent protective film is preferably from 1to 80 μm. When the first and second transparent protective films areprovided, at least one of the first and second transparent protectivefilms preferably has a thickness of 60 μm or less, more preferably 10 to60 μm, and even more preferably 10 to 50 μm so that irregularitiesderived from the polarizing plate can be kept at a low level.

The first and second transparent protective films each preferably have athickness of 60 μm or less, more preferably 10 to 60 μm, and even moverpreferably 10 to 50 μm.

The second transparent protective film generally has a haze value of 1%or less, preferably 0.5% or less, more preferably 0.3% or less. Atransparent protective film made of any of the above materials can beused as the second transparent protective film without modification.

The polarizer may be bonded to the first and/or second transparentprotective film with an adhesive. Examples of such an adhesive includeisocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives,vinyl latexes, and aqueous polyesters. The adhesive is generally used inthe form of an aqueous solution, which generally has a solids content of0.5 to 60% by weight. Besides the above, an active energy ray-curableadhesive such as an ultraviolet-curable adhesive or an electronbeam-curable adhesive may also be used as the adhesive to bond thepolarizer to the transparent protective film. Electron beam-curableadhesives for polarizing plates exhibit good adhesion to the transparentprotective film, especially to acrylic resins. In the adhesive used inthe invention may contain a metal compound filler.

An optical film except the polarizing plate may be exemplified as otheroptical layers, such as a reflective plate, a transflective plate, aretardation plate (a half wavelength plate and a quarter wavelengthplate included), a viewing angle compensation film, a brightnessenhancement film, a surface treatment film or the like, which may beused for formation of a liquid crystal display etc. These are used inpractice as an optical film, or as one layer or two layers or more ofoptical layers laminated with polarizing plate.

A pressure-sensitive adhesive polarizing plate as an example of thepressure-sensitive adhesive optical film of the invention is placed onthe viewer side when used to form an image display such as a liquidcrystal display. In this case, the pressure-sensitive adhesivepolarizing plate may be used in combination with any other optical filmto form an image display. In a liquid crystal display, thepressure-sensitive adhesive polarizing plate of the invention is used asa polarizing plate on the viewer side of a liquid crystal cell. Any typeof polarizing plate may be placed on the opposite side of the liquidcrystal cell.

Although an optical film with the above described optical layerlaminated to the polarizing plate may be formed by a method in whichlaminating is separately carried out sequentially in manufacturingprocess of a liquid crystal display or the like, an optical film in aform of being laminated beforehand has an outstanding advantage that ithas excellent stability in quality and assembly workability, and thusmanufacturing processes ability of a liquid crystal display or the likemay be raised. Proper adhesion means, such as a pressure-sensitiveadhesive layer, may be used for laminating. On the occasion of adhesionof the above described polarizing plate and other optical films, theoptical axis may be set as a suitable configuration angle according tothe target retardation characteristics or the like.

Examples of the retardation plate include a birefringent film producedby uniaxially or biaxially stretching a polymer material, an orientedliquid crystal polymer film, and an oriented liquid crystal polymerlayer supported on a film. The thickness of the retardation plate isgenerally, but not limited to, from about 10 to about 150 μm. Theretardation plate preferably has a thickness of 60 μm or less, morepreferably 10 to 60 μm, and even more preferably 10 to 50 μm so thatirregularities derived from the polarizing plate can be kept at a lowlevel.

Examples of the polymer material include polyvinyl alcohol, polyvinylbutyral, poly(methyl vinyl ether), poly(hydroxyethyl acrylate),hydroxyethyl cellulose, hydroxypropyl cellulose, methylcellulose,polycarbonate, polyarylate, polysulfone, polyethylene terephthalate,polyethylene naphthalate, polyethersulfone, polyphenylene sulfide,polyphenylene oxide, polyallylsulfone, polyamide, polyimide, polyolefin,polyvinyl chloride, cellulose resins, cyclic polyolefin resins(norbornene reins), and various types of binary or ternary copolymersthereof, graft copolymers thereof, and any blend thereof. Any of thesepolymer materials may be formed into an oriented product (a stretchedfilm) by stretching or the like.

Examples of the liquid crystal polymer include various main-chain orside-chain types having a liquid crystal molecular orientationproperty-imparting conjugated linear atomic group (mesogen) introducedin a main or side chain of a polymer. Examples of the main chain typeliquid crystal polymer include polymers having a mesogen group bondedthereto via a flexibility-imparting spacer moiety, such as nematicallyordered polyester liquid-crystalline polymers, discotic polymers, andcholesteric polymers. For example, the side-chain type liquid crystalpolymer may be a polymer comprising: a main chain skeleton ofpolysiloxane, polyacrylate, polymethacrylate, or polymalonate; and aside chain having a mesogen moiety that comprises a nematicorientation-imparting para-substituted cyclic compound unit and isbonded thereto via a spacer moiety comprising a conjugated atomic group.For example, any of these liquid crystal polymers may be applied by aprocess that includes spreading a solution of the liquid crystallinepolymer on an alignment surface such as a rubbed surface of a thin filmof polyimide, polyvinyl alcohol or the like, formed on the glass plate,and an obliquely vapor-deposited silicon oxide surface, andheat-treating it.

The retardation plate may have any appropriate retardation depending onthe intended use such as compensation for coloration, viewing angle, orthe like due to the birefringence of various wave plates or liquidcrystal layers. Two or more types of retardation plates may also belaminated to provide controlled optical properties, includingretardation.

The optical film to be used preferably has a haze value of 15% or less.Examples of the optical film may include those listed above for thetransparent protective film. The optical film with a haze value of 15%or less is suitable for use as a base film to be bonded to a front faceplate or a touch panel. A surface treatment film with a haze value of15% or less can be used as the optical film. The surface treatment filmcan be obtained by subjecting the base film to a surface treatment.

The haze value is preferably 1% or less, more preferably 0.5% or less,and even more preferably 0.3% or less. Generally, in view of strength,workability such as handleability, thin layer formability, or otherproperties, the thickness of the optical film with a haze value of 15%or less is preferably from 1 to 80 μm. The optical film with a hazevalue of 15% or less preferably has a thickness of 60 μm or less, morepreferably 10 to 60 μm, and even more preferably 10 to 50 μm so thatirregularities on the optical film can be kept at a low level.

Examples of the surface treatment film include a hard-coat film for usein imparting scratch resistance to the surface, an antiglare treatmentfilm for preventing glare on image displays, and an anti-reflection filmsuch as an anti-reflective film or a low-reflective film, etc. The frontface plate is provided on and bonded to the surface of an image displaysuch as a liquid crystal display, an organic EL display, a CRT, or a PDPto protect the image display or to provide a high-grade appearance or adifferentiated design. The front face plate is also used as a supportfor a λ/4 plate in a 3D-TV. In a liquid crystal display, for example,the front face plate is provided above a polarizing plate on the viewerside. When the pressure-sensitive adhesive layer according to theinvention is used, the same effect can be produced using a plastic basematerial such as a polycarbonate or poly (methyl methacrylate) basematerial for the front face plate, as well as using a glass basematerial.

The pressure-sensitive adhesive layer provided on the optical film ismade from a pressure-sensitive adhesive. Any of variouspressure-sensitive adhesives may be used, such as a rubber-basedpressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, asilicone-based pressure-sensitive adhesive, a urethane-basedpressure-sensitive adhesive, a vinyl alkyl ether-basedpressure-sensitive adhesive, a polyvinyl alcohol-basedpressure-sensitive adhesive, a polyvinylpyrrolidone-basedpressure-sensitive adhesive, a polyacrylamide-based pressure-sensitiveadhesive, or a cellulose-based pressure-sensitive adhesive. Thepressure-sensitive adhesive base polymer is selected depending on thetype of the pressure-sensitive adhesive.

Among the above pressure-sensitive adhesives, an acrylicpressure-sensitive adhesive is preferably used because it has a highlevel of optical transparency and weather resistance or heat resistanceand exhibits appropriate wettability and pressure-sensitive adhesiveproperties such as appropriate cohesiveness and tackiness.

The acrylic pressure-sensitive adhesive includes, as a base polymer, a(meth)acryl-based polymer having an alkyl (meth)acrylate monomer unit inthe main skeleton. As used therein, the term “alkyl (meth)acrylate”refers to alkyl acrylate and/or alkyl methacrylate, and “(meth)” is usedin the same meaning in the description. For example, the alkyl(meth)acrylate used to form the main skeleton of the (meth)acryl-basedpolymer may have a straight or branched chain alkyl group of 1 to 18carbon atoms. For example, the alkyl group may be methyl, ethyl, propyl,isopropyl, butyl, isobutyl, amyl, hexyl, cyclohexyl, heptyl,2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, dodecyl, isomyristyl,lauryl, tridecyl, pentadecyl, hexadecyl, heptadecyl, or octadecyl. Thesemay be used alone or in any combination. The average carbon number ofthe alkyl groups is preferably from 3 to 9.

An aromatic ring-containing alkyl (meth)acrylate may also be used, suchas phenoxyethyl(meth)acrylate or benzyl (meth)acrylate. The aromaticring-containing alkyl (meth)acrylate may be used to form a polymer, andsuch a polymer may be mixed with any of the (meth)acryl-based polymerslisted above when uses. In view of transparency, a copolymer of thealkyl (meth)acrylate and the aromatic ring-containing alkyl(meth)acrylate is preferably used.

In order to improve tackiness or heat resistance, one or morecopolymerizable monomers having an unsaturated double bond-containingpolymerizable functional group such as a (meth)acryloyl group or a vinylgroup may be introduced into the (meth)acryl-based polymer bycopolymerization. Examples of such copolymerizable monomers includehydroxyl group-containing monomers such as 2-hydroxyethyl(meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl(meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl(meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl(meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate;carboxyl group-containing monomers such as (meth)acrylic acid,carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconicacid, maleic acid, fumaric acid, and crotonic acid; acid anhydridegroup-containing monomers such as maleic anhydride and itaconicanhydride; caprolactone adducts of acrylic acid; sulfonic acidgroup-containing monomers such as styrenesulfonic acid, allylsulfonicacid, 2-(meth)acrylamido-2-methylpropanesulfonic acid,(meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and(meth)acryloyloxynaphthalenesulfonic acid; and phosphategroup-containing monomers such as 2-hydroxyethylacryloyl phosphate.

Examples of such a monomer for modification also include (N-substituted)amide monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide,N-butyl(meth)acrylamide, N-methylol (meth)acrylamide, andN-methylolpropane (meth)acrylamide; alkylaminoalkyl (meth)acrylatemonomers such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl(meth)acrylate, and tert-butylaminoethyl (meth)acrylate; alkoxyalkyl(meth)acrylate monomers such as methoxyethyl (meth)acrylate andethoxyethyl (meth)acrylate; succinimide monomers such asN-(meth)acryloyloxymethylenesuccinimide,N-(meth)acryloyl-6-oxyhexamethylenesuccinimide,N-(meth)acryloyl-8-oxyoctamethylenesuccinimide, andN-acryloylmorpholine; maleimide monomers such as N-cyclohexylmaleimide,N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; anditaconimide monomers such as N-methylitaconimide, N-ethylitaconimide,N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide,N-cyclohexylitaconimide, and N-laurylitaconimide.

Examples of modification monomers that may also be used include vinylmonomers such as vinyl acetate, vinyl propionate, N-vinylpyrrolidone,methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine,vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole,vinyloxazole, vinylmorpholine, N-vinylcarboxylic acid amides, styrene,α-methylstyrene, and N-vinylcaprolactam; cyanoacrylate monomers such asacrylonitrile and methacrylonitrile; epoxy group-containing acrylicmonomers such as glycidyl (meth)acrylate; glycol acrylic ester monomerssuch as polyethylene glycol (meth)acrylate, polypropylene glycol(meth)acrylate, methoxyethylene glycol (meth)acrylate, andmethoxypolypropylene glycol (meth)acrylate; and acrylate ester monomerssuch as tetrahydrofurfuryl (meth)acrylate, fluoro(meth)acrylate,silicone (meth)acrylate, and 2-methoxyethyl acrylate. Examples alsoinclude isoprene, butadiene, isobutylene, and vinyl ether.

Besides the above, a silicon atom-containing silane monomer may beexemplified as the copolymerizable monomer. Examples of the silanemonomers include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane,vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane,4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane,8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane,10-acryloyloxydecyltrimethoxysilane,10-methacryloyloxydecyltriethoxysilane, and10-acryloyloxydecyltriethoxysilane.

Copolymerizable monomers that may be used also include polyfunctionalmonomers having two or more unsaturated double bonds such as(meth)acryloyl groups or vinyl groups, which include (meth)acrylateesters of polyhydric alcohols, such as tripropylene glycoldi(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate,neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate,pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate,dipentaerythritol penta(meth)acrylate, dipentaerythritolhexa(meth)acrylate, and caprolactone-modified dipentaerythritolhexa(meth)acrylate; and compounds having a polyester, epoxy or urethaneskeleton to which two or more unsaturated double bonds are added in theform of functional groups such as (meth)acryloyl groups or vinyl groupsin the same manner as the monomer component, such aspolyester(meth)acrylates, epoxy(meth)acrylates andurethane(meth)acrylates.

Among these copolymerizable monomers, hydroxyl group-containing monomersor carboxyl group-containing monomers are preferably used in view oftackiness or durability. When the pressure-sensitive adhesivecomposition contains a crosslinking agent, these copolymerizablemonomers can serve as a reactive site with the crosslinking agent. Suchhydroxyl group-containing monomers or carboxyl group-containing monomersare highly reactive with intermolecular crosslinking agents andtherefore are preferably used to improve the cohesiveness or heatresistance of the resulting pressure-sensitive adhesive layer.

A hydroxyl group-containing monomer and a carboxyl group-containingmonomer may be added as copolymerizable monomers. In this case, thecopolymerizable monomers may be used in the above content. Specifically,the content of the carboxyl group-containing monomer is preferably from0.1 to 10% by weight, and the content of the hydroxyl group-containingmonomer is preferably from 0.01 to 2% by weight. The content of thecarboxyl group-containing monomer is more preferably from 0.2 to 8% byweight, even more preferably from 0.6 to 6% by weight. The content ofthe hydroxyl group-containing monomer is more preferably from 0.03 to1.5% by weight, even more preferably from 0.05 to 1% by weight.

In an embodiment of the invention, the (meth)acryl-based polymer usedgenerally has a weight average molecular weight in the range of 300,000to 3,000,000. In view of durability, particularly in view of heatresistance, the weight average molecular weight of the (meth)acryl-basedpolymer used is preferably from 800,000 to 3,000,000, more preferablyfrom 1,400,000 to 2,700,000, more preferably from 1,700,000 to2,500,000, more preferably from 1,800,000 to 2,400,000. If the weightaverage molecular weight is less than 300,000, it is not preferred inview of heat resistance. If a weight average molecular weight is morethan 3,000,000, it is not preferred because a laminating ability or anadhesive strength may decrease. The weight average molecular weightrefers to the value obtained by measurement by gel permeationchromatography (GPC) and conversion of the measured value into thepolystyrene-equivalent value. The degree of dispersion (weight averagemolecular weight/number average molecular weight) is preferably from 1.8to 10, more preferably from 2 to 7, and even more preferably from 2 to5.

For the production of the (meth)acryl-based polymer, any appropriatemethod may be selected from known production methods such as solutionpolymerization, bulk polymerization, emulsion polymerization, andvarious radical polymerization methods. The resulting (meth)acryl-basedpolymer may be any type of copolymer such as a random copolymer, a blockcopolymer and a graft copolymer.

In a solution polymerization process, for example, ethyl acetate,toluene or the like is used as a polymerization solvent. In a specificsolution polymerization process, for example, the reaction is performedunder a stream of inert gas such as nitrogen at a temperature of about50 to about 70° C. for about 5 to about 30 hours in the presence of apolymerization initiator.

Any appropriate polymerization initiator, chain transfer agent,emulsifying agent and so on may be selected and used for radicalpolymerization. The weight average molecular weight of the(meth)acryl-based polymer may be controlled by the reaction conditionsincluding the amount of addition of the polymerization initiator or thechain transfer agent and monomers concentration. The amount of theaddition may be controlled as appropriate depending on the type of thesematerials.

Examples of the polymerization initiator include, but are not limitedto, azo initiators such as 2,2′-azobisisobutylonitrile,2,2′-azobis(2-amidinopropane)dihydrochloride,2,2′-azobis[2-(5-methyl-2-imidazoline-2-yl)propane]dihydrochloride,2,2′-azobis(2-methylpropionamidine)disulfate,2′,2″-azobis(2-amidinopropane)dibasic acid,2,2′-azobis[2-(2-imidazolin-2-yl)propane]dibasic acid,2,2′-azobis(N,N′-dimethyleneisobutylamidine), and2,2′-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate (VA-057,manufactured by Wako Pure Chemical Industries, Ltd.); persulfates suchas potassium persulfate and ammonium persulfate; peroxide initiatorssuch as di(2-ethylhexyl)peroxydicarbonate,di(4-tert-butylcyclohexyl)peroxydicarbonate,di-sec-butylperoxydicarbonate, tert-butylperoxyneodecanoate,tert-hexylperoxypivalate, tert-butylperoxypivalate, dilauroyl peroxide,di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoyl peroxide,tert-butylperoxyisobutylate, 1,1-di(tert-hexylperoxy)cyclohexane,tert-butylhydroperoxide, and hydrogen peroxide; and redox systeminitiators of a combination of a peroxide and a reducing agent, such asa combination of a persulfate and sodium hydrogen sulfite and acombination of a peroxide and sodium ascorbate. Examples of the reducingagent include reducing organic compounds such as ascorbic acid,erythorbic acid, tartaric acid, citric acid, glucose, and metal saltssuch as a sodium salts of formaldehyde sulfoxylate or the like; reducinginorganic compounds such as sodium thiosulfate, sodium sulfite, sodiumbisulfite, and sodium metabisulfite; and ferrous chloride, Rongalite,and thiourea dioxide.

One of the above polymerization initiators may be used alone, or two ormore thereof may be used in a mixture. The total content of thepolymerization initiator is preferably from about 0.005 to 1 part byweight, more preferably from about 0.02 to about 0.5 parts by weight,based on 100 parts by weight of the monomer.

For example, when 2,2′-azobisisobutyronitrile is used as apolymerization initiator for the production of the (meth)acryl-basedpolymer with the above weight average molecular weight, thepolymerization initiator is preferably used in a content of from about0.06 to 0.2 parts by weight, more preferably of from about 0.08 to 0.175parts by weight, based on 100 parts by weight of the total content ofthe monomer components.

Examples of the chain transfer agent include lauryl mercaptan, glycidylmercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid,2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol. One of thesechain transfer agents may be used alone, or two or more thereof may beused in a mixture. The total content of the chain transfer agent ispreferably 0.1 parts by weight or less, based on 100 parts by weight ofthe total content of the monomer components.

The surfactant (emulsifying agent) used is not particularly limited, andmay be any of various surfactants commonly used in emulsionpolymerization. For example, the surfactant may be an anionic ornonionic surfactant. Examples of the anionic surfactant include higherfatty acid salts such as sodium oleate; alkylarylsulfonate salts such assodium dodecylbenzenesulfonate; alkylsulfate ester salts such as sodiumlaurylsulfate and ammonium laurylsulfate; polyoxyethylene alkyl ethersulfate ester salts such as sodium polyoxyethylene lauryl ether sulfate;polyoxyethylene alkyl aryl ether sulfate ester salts such as sodiumpolyoxyethylene nonyl phenyl ether sulfate; alkyl sulfosuccinic acidester salts such as sodium monooctyl sulfosuccinate, sodium dioctylsulfosuccinate, and sodium polyoxyethylene lauryl sulfosuccinate, andderivatives thereof; and polyoxyethylene distyrenated phenyl ethersulfate ester salts; polyoxyethylene distyrenated phenyl ether sulfateester salts; sodium naphthalenesulfonate-formalin condensate. Examplesof the nonionic surfactant include polyoxyethylene alkyl ethers such aspolyoxyethylene lauryl ether and polyoxyethylene stearyl ether;polyoxyethylene alkyl phenyl ethers such as polyoxyethylene octyl phenylether and polyoxyethylene nonyl phenyl ether; sorbitan higher fatty acidesters such as sorbitan monolaurate, sorbitan monostearate, and sorbitantrioleate; polyoxyethylene sorbitan higher fatty acid esters such aspolyoxyethylene sorbitan monolaurate; polyoxyethylene higher fatty acidesters such as polyoxyethylene monolaurate and polyoxyethylenemonostearate; glycerin higher fatty acid esters such as oleic acidmonoglyceride and stearic acid monoglyceride; andpolyoxyethylene-polyoxypropylene block copolymers, and polyoxyethylenedistyrenated phenyl ether.

Besides the non-reactive surfactants, a reactive surfactant having anethylenic unsaturated double bond-containing radically-polymerizablefunctional group may also be used. The reactive surfactant may be aradical-polymerizable surfactant prepared by introducing aradical-polymerizable functional group (radically reactive group) suchas a propenyl group or an allyl ether group into the anionic surfactantor the nonionic surfactant. These surfactants may be appropriately usedalone or in any combination. Among these surfactants, theradical-polymerizable surfactant having a radical-polymerizablefunctional group is preferably used in view of the stability of theaqueous dispersion or the durability of the pressure-sensitive adhesivelayer.

Examples of anionic reactive surfactants include alkyl ether surfactants(examples of commercially available products include AQUALON KH-05,KH-10, and KH-20 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., ADEKAREASOAP SR-10N and SR-20N manufactured by ADEKA CORPORATION, LATEMULPD-104 manufactured by Kao Corporation, and others); sulfosuccinic acidester surfactants (examples of commercially available products includeLATEMUL S-120, S-120A, S-180P, and S-180A manufactured by KaoCorporation and ELEMINOL JS-2 manufactured by Sanyo Chemical Industries,Ltd., and others); alkyl phenyl ether surfactants or alkyl phenyl estersurfactants (examples of commercially available products include AQUALONH-2855A, H-3855B, H-3855C, H-3856, HS-05, HS-10, HS-20, HS-30, BC-05,BC-10, and BC-20 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., andADEKA REASOAP SDX-222, SDX-223, SDX-232, SDX-233, SDX-259, SE-10N, andSE-20N manufactured by ADEKA CORPORATION); (meth)acrylate sulfate estersurfactants (examples of commercially available products include ANTOXMS-60 and MS-2N manufactured by Nippon Nyukazai Co., Ltd., ELEMINOLRS-30 manufactured by Sanyo Chemical Industries Co., Ltd., and others);and phosphoric acid ester surfactants (examples of commerciallyavailable products include H-3330PL manufactured by Dai-ichi KogyoSeiyaku Co., Ltd. ADEKA REASOAP PP-70 manufactured by ADEKA CORPORATION,and others). Examples of nonionic reactive surfactants include alkylether surfactants (examples of commercially available products includeADEKA REASOAP ER-10, ER-20, ER-30, and ER-40 manufactured by ADEKACORPORATION, LATEMUL PD-420, PD-430, and PD-450 manufactured by KaoCorporation, and others); alkyl phenyl ether surfactants or alkyl phenylester surfactants (examples of commercially available products includeAQUALON RN-10, RN-20, RN-30, and RN-50 manufactured by Dai-ichi KogyoSeiyaku Co., Ltd., ADEKA REASOAP NE-10, NE-20, NE-30, and NE-40manufactured by ADEKA CORPORATION, and others); and (meth)acrylatesulfate ester surfactants (examples of commercially available productsinclude RMA-564, RMA-568, and RMA-1114 manufactured by Nippon NyukazaiCo., Ltd, and others).

The content of the surfactant is preferably from 0.6 to 5 parts byweight based on 100 parts by weight of the monomers. Thepressure-sensitive adhesive properties, polymerization stability, andmechanical stability can be improved by adjusting the content of thesurfactant. The content of the surfactant is more preferably from 0.6 to4 parts by weight.

The pressure-sensitive adhesive used to form the pressure-sensitiveadhesive layer may further contain a crosslinking agent in addition tothe base polymer such as the (meth)acryl-based polymer. An organiccrosslinking agent or a polyfunctional metal chelate may also be used asthe crosslinking agent. Examples of the organic crosslinking agentinclude an isocyanate crosslinking agent, an epoxy crosslinking agents,a peroxide crosslinking agents and an imine crosslinking agents. Thepolyfunctional metal chelate may include a polyvalent metal and anorganic compound that is covalently or coordinately bonded to the metal.Examples of the polyvalent metal atom include Al, Cr, Zr, Co, Cu, Fe,Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, and Ti. Theorganic compound has a covalent or coordinate bond-forming atom such asan oxygen atom. Examples of the organic compound include alkyl esters,alcohol compounds, carboxylic acid compounds, ether compounds, andketone compounds.

The crosslinking agent to be used is preferably selected from anisocyanate crosslinking agent and/or a peroxide crosslinking agent.Examples of such a compound for the isocyanate crosslinking agentinclude isocyanate monomers such as tolylene diisocyanate,chlorophenylene diisocyanate, tetramethylene diisocyanate, xylylenediisocyanate, diphenylmethane diisocyanate, and hydrogenateddiphenylmethane diisocyanate, and isocyanate compounds produced byadding any of these isocyanate monomers to trimethylolpropane or thelike; and urethane prepolymer type isocyanates produced by the additionreaction of isocyanurate compounds, burette type compounds, or polyetherpolyols, polyester polyols, acrylic polyols, polybutadiene polyols,polyisoprene polyols, or the like. Particularly preferred is apolyisocyanate compound such as one selected from the group consistingof hexamethylene diisocyanate, hydrogenated xylylene diisocyanate, andisophorone diisocyanate, or a derivative thereof. Examples of oneselected from the group consisting of hexamethylene diisocyanate,hydrogenated xylylene diisocyanate, and isophorone diisocyanate, or aderivative thereof include hexamethylene diisocyanate, hydrogenatedxylylene diisocyanate, isophorone diisocyanate, polyol-modifiedhexamethylene diisocyanate, polyol-modified hydrogenated xylylenediisocyanate, trimer-type hydrogenated xylylene diisocyanate, andpolyol-modified isophorone diisocyanate. The listed polyisocyanatecompounds are preferred, because their reaction with a hydroxyl groupquickly proceeds as if an acid or a base contained in the polymer actsas a catalyst, which particularly contributes to the rapidness of thecrosslinking.

Any peroxide capable of generating active radical species by heating orphotoirradiation and promoting the crosslinking of the base polymer inthe pressure-sensitive adhesive composition may be appropriately used.In view of workability and stability, a peroxide with a one-minutehalf-life temperature of 80° C. to 160° C. is preferably used, and aperoxide with a one-minute half-life temperature of 90° C. to 140° C. ismore preferably used.

Examples of the peroxide for use in the invention includedi(2-ethylhexyl)peroxydicarbonate (one-minute half-life temperature:90.6° C.), di(4-tert-butylcyclohexyl)peroxydicarbonate (one-minutehalf-life temperature: 92.1° C.), di-sec-butyl peroxydicarbonate(one-minute half-life temperature: 92.4° C.), tert-butylperoxyneodecanoate (one-minute half-life temperature: 103.5° C.),tert-hexyl peroxypivalate (one-minute half-life temperature: 109.1° C.),tert-butyl peroxypivalate (one-minute half-life temperature: 110.3° C.),dilauroyl peroxide (one-minute half-life temperature: 116.4° C.),di-n-octanoylperoxide (one-minute half-life temperature: 117.4° C.),1,1,3,3-tetramethylbutylperoxy-2-ethyl hexanoate (one-minute half-lifetemperature: 124.3° C.), di(4-methylbenzoyl) peroxide (one-minutehalf-life temperature: 128.2° C.), dibenzoyl peroxide (one-minutehalf-life temperature: 130.0° C.), tert-butyl peroxyisobutylate(one-minute half-life temperature: 136.1° C.), and1,1-di(tert-hexylperoxy)cyclohexane (one-minute half-life temperature:149.2° C.). In particular, di(4-tert-butylcyclohexyl)peroxydicarbonate(one-minute half-life temperature: 92.1° C.), dilauroyl peroxide(one-minute half-life temperature: 116.4° C.), dibenzoyl peroxide(one-minute half-life temperature: 130.0° C.), or the like is preferablyused, because they can provide high crosslinking reaction efficiency.

The half life of the peroxide is an indicator of how fast the peroxidecan be decomposed and refers to the time required for the amount of theperoxide to reach one half of its original value. The decompositiontemperature required for a certain half life and the half life timeobtained at a certain temperature are shown in catalogs furnished bymanufacturers, such as “Organic Peroxide Catalog, 9th Edition, May,2003” furnished by NOF CORPORATION.

The amount of the crosslinking agent to be used is preferably from 0.01to 20 parts by weight, more preferably from 0.03 to 10 parts by weight,based on 100 parts by weight of the base polymer such as the(meth)acryl-based polymer. If the amount of the crosslinking agent isless than 0.01 parts by weight, the cohesive strength of thepressure-sensitive adhesive may tend to be insufficient, and foaming mayoccur during heating. If the amount of the crosslinking agent is morethan 20 parts by weight, the humidity resistance may be insufficient, sothat peeling may easily occur in a reliability test or the like.

One of the isocyanate crosslinking agents may be used alone, or amixture of two or more of the isocyanate crosslinking agents may beused. The total content of the polyisocyanate compound crosslinkingagent(s) is preferably from 0.01 to 2 parts by weight, more preferablyfrom 0.02 to 2 parts by weight, even more preferably from 0.05 to 1.5parts by weight, based on 100 parts by weight of the (meth)acryl-basedpolymer. The content may be appropriately controlled taking into accountthe cohesive strength or the prevention of peeling in a durability testor the like.

One of the peroxide crosslinking agents may be used alone, or a mixtureof two or more of the peroxide crosslinking agent may be used. The totalcontent of the peroxide(s) is preferably from 0.01 to 2 parts by weight,more preferably from 0.04 to 1.5 parts by weight, even more preferablyfrom 0.05 to 1 part by weight, based on 100 parts by weight of the(meth)acryl-based polymer. The content of the peroxide(s) may beappropriately selected in this range in order to control theworkability, reworkability, crosslink stability or peeling properties.

The amount of decomposition of the peroxide may be determined bymeasuring the peroxide residue after the reaction process by highperformance liquid chromatography (HPLC).

More specifically, for example, after the reaction process, about 0.2 gof each pressure-sensitive adhesive composition is taken out, immersedin 10 ml of ethyl acetate, subjected to shaking extraction at 25° C. and120 rpm for 3 hours in a shaker, and then allowed to stand at roomtemperature for 3 days. Thereafter, 10 ml of acetonitrile is added, andthe mixture is shaken at 25° C. and 120 rpm for 30 minutes. About 10 μlof the liquid extract obtained by filtration through a membrane filter(0.45 μm) is subjected to HPLC by injection and analyzed so that theamount of the peroxide after the reaction process is determined.

The pressure-sensitive adhesive of the invention may further contain asilane coupling agent. The durability or the reworkability can beimproved using the silane coupling agent. Examples of silane couplingagent include epoxy group-containing silane coupling agents such as3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane,3-glycidoxypropylmethyldiethoxysilane, and2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containingsilane coupling agents such as 3-aminopropyltrimethoxysilane,N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine; (meth)acrylicgroup-containing silane coupling agents such as3-acryloxypropyltrimethoxysilane and3-methacryloxypropyltriethoxysilane; and isocyanate group-containingsilane coupling agents such as 3-isocyanatepropyltriethoxysilane.

One of the silane coupling agents (E) may be used alone, or a mixture oftwo or more of the silane coupling agents. The total content of thesilane coupling agent(s) is preferably from 0.001 to 5 parts by weight,more preferably from 0.01 to 1 part by weight, even more preferably from0.02 to 1 part by weight, still more preferably from 0.05 to 0.6 partsby weight, based on 100 parts by weight of the (meth)acryl-basedpolymer. The content of the silane coupling agent may be appropriatelyamount in order to control improve durability and maintain adhesivestrength to the optical member such as a liquid crystal cell.

The pressure-sensitive adhesive composition of the invention may alsocontain any other known additive. For example, a powder such as acolorant and a pigment, a tackifier, a dye, a surfactant, a plasticizer,a surface lubricant, a leveling agent, a softening agent, anantioxidant, an age resister, a light stabilizer, an ultravioletabsorbing agent, a polymerization inhibitor, an inorganic or organicfiller, a metal powder, or a particle- or foil-shaped material may beadded as appropriate depending on the intended use. A redox systemincluding an added reducing agent may also be used in the controllablerange.

The pressure-sensitive adhesive layer is made from thepressure-sensitive adhesive. The pressure-sensitive adhesive isgenerally used as a coating liquid, which may be in various forms suchas an organic solvent-based liquid, a water-based liquid, and an aqueousdispersion type liquid (emulsion type liquid) depending on how toprepare the base polymer. The solid concentration of thepressure-sensitive adhesive coating liquid can be adjusted depending oneach form. In general, for example, an organic solvent-basedpressure-sensitive adhesive coating liquid preferably has a solidconcentration of 5 to 50% by weight, more preferably 8 to 40% by weight,and even more preferably 20 to 35% by weight. In general, a water-basedor aqueous dispersion-type pressure-sensitive adhesive coating liquidpreferably has a solid concentration of 20 to 70% by weight, and morepreferably 30 to 65% by weight. In the preparation of each example ofthe pressure-sensitive adhesive coating liquid, each pressure-sensitiveadhesive can be diluted with any of various organic solvents (for anorganic solvent-type pressure-sensitive adhesive) or with water (for awater-based or aqueous dispersion-type pressure-sensitive adhesive) sothat the solid concentration and the viscosity of the pressure-sensitiveadhesive coating liquid can be adjusted.

The thickness of the pressure-sensitive adhesive layer is typically, butnot limited to, about 1 to about 100 μm, preferably 2 to 50 μm, morepreferably 2 to 40 μm, and even more preferably 5 to 35 μm.

The thickness (μm) of the pressure-sensitive adhesive layer is adjustedto have a standard deviation of 0.12 μm or less. Adjusting the standarddeviation to 0.12 μm or less makes it possible to reduce the problem ofunevenness in visibility caused by a pressure-sensitive adhesive opticalfilm, even when it has a clear appearance. The standard deviation ispreferably 0.08 μm or less, and more preferably 0.06 μm or less.

The pressure-sensitive adhesive optical film of the invention having apressure-sensitive adhesive layer with a thickness (μm) standarddeviation of 0.12 μm or less is typically produced

by a process (A) including the steps of:

(1A) applying a pressure-sensitive adhesive coating liquid with aviscosity Y (P) to an optical film to form a coating with a thickness X(μm); and

(2A) drying the applied pressure-sensitive adhesive coating liquid toform a pressure-sensitive adhesive layer, or

by a process (B) including the steps of:

(1B) applying a pressure-sensitive adhesive coating liquid with aviscosity Y (P) to a release film to form a coating with a thickness X(μm);

(2B) drying the applied pressure-sensitive adhesive coating liquid toform a pressure-sensitive adhesive layer; and

(3) bonding the pressure-sensitive adhesive layer, which is formed onthe release film, to an optical film.

The applying step (1A) of the process (A) and the applying step (1B) ofthe process (B) are each performed in such a manner that the viscosity Yof the pressure-sensitive adhesive coating liquid and the thickness X ofthe coating are adjusted to satisfy the relation 0.8X−Y≦68. Adjustingthe viscosity Y of the pressure-sensitive adhesive coating liquid andthe thickness X of the coating to satisfy the relation 0.8X−Y≦68 makesit possible to form a highly-smooth pressure-sensitive adhesive layerwith a very low level of irregularities in thickness. The process (A) or(B) makes it possible to form a pressure-sensitive adhesive layer with athickness (μm) standard deviation of 0.12 μm or less. If the value of(0.8X−Y) is more than 68, the pressure-sensitive adhesive optical filmcannot reduce the problem of unevenness in visibility. The value of(0.8X−Y) is preferably 60 or less, and more preferably 50 or less. Inview of the coatability of the pressure-sensitive adhesive coatingliquid, the value of (0.8X−Y) is preferably −144 or more.

For uniform application of the pressure-sensitive adhesive coatingliquid, the viscosity Y of the pressure-sensitive adhesive coatingliquid is preferably adjusted to fall within the range of 2 to 160 P. Inthe case of an organic solvent-based pressure-sensitive adhesive, theviscosity Y of the pressure-sensitive adhesive coating liquid ispreferably from 5 to 160 P, more preferably from 10 to 150 P, even morepreferably from 20 to 140 P, still more preferably from 40 to 140 P. Inthe case of a water-based or aqueous dispersion-type pressure-sensitiveadhesive, the viscosity Y of the pressure-sensitive adhesive coatingliquid is preferably from 2 to 100 P, more preferably from 5 to 50 P,even more preferably from 10 to 40 P. If the viscosity Y of thepressure-sensitive adhesive coating liquid is too low, the appliedpressure-sensitive adhesive may have a degraded appearance, and if theviscosity Y of the pressure-sensitive adhesive coating liquid is toohigh, the coating appearance may be degraded, and it may be difficult tofeed the liquid, which will undesirably reduce workability.

The thickness X of the coating made of the pressure-sensitive adhesivecoating liquid is preferably adjusted to fall within the range of 20 to250 μm so that the pressure-sensitive adhesive coating liquid can beuniformly applied. The coating thickness X is preferably from 30 to 230μm, and more preferably from 50 to 200 μm. The coating thickness Xshould be determined taking into account the thickness (post-dryingthickness) of the pressure-sensitive adhesive layer to be formed. If thecoating thickness X is too large or small, the coating appearance may bedegraded.

Various methods may be used in the applying step (1A) or (1B). Specificexamples of such methods include roll coating, kiss roll coating,gravure coating, reverse coating, roll brush coating, spray coating, diproll coating, bar coating, knife coating, air knife coating, curtaincoating, lip coating, and extrusion coating with a die coater or thelike. Among such methods, a die coater method is preferred, and a diecoater method using a fountain die or a slot die is particularlypreferred. In the process (A), an optical film is subjected to theapplying step (1A). In the process (B), a release film is subjected tothe applying step (1B).

In the process (A) or (B), the step (2A) or (2B) is performed to form apressure-sensitive adhesive layer. In the forming step (2A) or (2B), theapplied pressure-sensitive adhesive coating liquid is generally dried.The drying temperature is preferably from 40° C. to 200° C., morepreferably from 50° C. to 180° C., in particular, preferably from 70° C.to 170° C. The drying time to be used is appropriately selected. Thedrying time is preferably from 5 seconds to 20 minutes, more preferablyfrom 5 seconds to 10 minutes, in particular, preferably from 10 secondsto 5 minutes.

When the pressure-sensitive adhesive contains a crosslinking agent, itis preferred that the total content of the crosslinking agent should beadjusted for the formation of the pressure-sensitive adhesive layer andthat the effect of the crosslinking temperature and the crosslinkingtime should be carefully considered. The crosslinking treatment may beperformed at the temperature during the drying process thepressure-sensitive adhesive layer, or may be separately performed afterthe drying process.

In the process (A), the pressure-sensitive adhesive layer is formeddirectly on the optical film by the step (2A) so that thepressure-sensitive adhesive optical film is obtained. In the process(B), the pressure-sensitive adhesive layer is formed on the release filmby the step (2B), and then the pressure-sensitive adhesive layer istransferred to the optical film by the step (3) of bonding thepressure-sensitive adhesive layer to the optical film so that thepressure-sensitive adhesive optical film is obtained. When thepressure-sensitive adhesive polarizing plate shown in FIG. 2 or 3 isprepared, the pressure-sensitive adhesive plate A1 or A2 is used as theoptical film 1, and the pressure-sensitive adhesive layer 2 is formed ona side of the polarizing plate A1 or A2 opposite to its side where thefirst transparent protective film (b1) is provided, in both of theprocesses (A) and (B).

Examples of the material used to form the release film include a plasticfilm such as a polyethylene, polypropylene, polyethylene terephthalate,or polyester film, a porous material such as paper, fabric, or nonwovenfabric, and an appropriate thin material such as a net, a foamed sheet,a metal foil, and a laminate thereof. Aplastic film is preferably used,because of its good surface smoothness.

Any plastic film capable of protecting the pressure-sensitive adhesivelayer may be used, examples of which include a polyethylene film, apolypropylene film, a polybutene film, a polybutadiene film, apolymethylpentene film, a polyvinyl chloride film, a vinyl chloridecopolymer film, a polyethylene terephthalate film, a polybutyleneterephthalate film, a polyurethane film, and an ethylene-vinyl acetatecopolymer film.

The thickness of the release film is generally from about 5 to about 200μm, preferably from about 5 to about 100 μm. If necessary, the separatormay be subjected to a release treatment and an antifouling treatmentwith a silicone, fluoride, long-chain alkyl, or fatty acid amide releaseagent, silica powder or the like, or subjected to an antistatictreatment of coating type, kneading and mixing type, vapor-depositiontype, or the like. In particular, when the surface of the release filmis appropriately subjected to a release treatment such as a siliconetreatment, a long-chain alkyl treatment, or a fluorine treatment, thereleasability from the pressure-sensitive adhesive layer can be furtherincreased.

The pressure-sensitive adhesive layer may be exposed. In such a case,the pressure-sensitive adhesive layer may be protected by the releasefilm until it is actually used. The release film may be used as is as aseparator for a pressure-sensitive adhesive optical film, so that theprocess can be simplified.

A surface of the optical film, provided that the surface is a side wherethe first protective film is not prepares if the optical film is thepolarizing plate, may also be coated with an anchor layer or subjectedto any adhesion-facilitating treatment such as a corona treatment or aplasma treatment so as to have improved adhesion to a pressure-sensitiveadhesive layer, and then the pressure-sensitive adhesive layer may beformed. The surface of the pressure-sensitive adhesive layer may also besubjected to an adhesion-facilitating treatment.

Materials that may be used to form the anchor layer preferably includean anchoring agent selected from polyurethane, polyester, polymerscontaining an amino group in the molecule, and polymers containing anoxazolinyl group in the molecule, in particular, preferably polymerscontaining an amino group in the molecule and polymers containing anoxazolinyl group in the molecule. Polymers containing an amino group inthe molecule and polymers containing an oxazolinyl group in the moleculeallow the amino group in the molecule or an oxazolinyl group in themolecule to react with a carboxyl group or the like in thepressure-sensitive adhesive or to make an interaction such as an ionicinteraction, so that good adhesion can be ensured.

Examples of polymers containing an amino group in the molecule includepolyethyleneimine, polyallylamine, polyvinylamine, polyvinylpyridine,polyvinylpyrrolidine, and a polymer of an amino group-containing monomersuch as dimethylaminoethyl acrylate.

The pressure-sensitive adhesive optical film such as pressure-sensitivepolarizing plate of the invention is preferably used to form varioustypes of image displays such as liquid crystal displays. Liquid crystaldisplays may be produced according to conventional techniques.Specifically, liquid crystal displays are generally produced byappropriately assembling a display panel such as a liquid crystal celland the pressure-sensitive polarizing plate and optionally othercomponents such as a lighting system and incorporating a driving circuitaccording to any conventional technique, except that thepressure-sensitive adhesive optical film of the invention is used. Anytype of liquid crystal cell may also be used such as a TN type, an STNtype, a n type, a VA type and an IPS type.

Suitable liquid crystal displays, such as liquid crystal display withwhich the above pressure-sensitive polarizing plate has been provided onone side or both sides of the display panel such as a liquid crystalcell, and with which a backlight or a reflective plate is used for alighting system may be manufactured. In this case, thepressure-sensitive polarizing plate of the invention may be provided onone side or both sides of the display panel such as a liquid crystalcell. When providing the pressure-sensitive polarizing plates on bothsides, they may be of the same type or of different type. Furthermore,in assembling a liquid crystal display, suitable parts, such asdiffusion plate, anti-glare layer, antireflection film, protectiveplate, prism array, lens array sheet, optical diffusion plate, andbacklight, may be installed in suitable position in one layer or two ormore layers.

Subsequently, organic electro luminescence equipment (organic ELdisplay: OLED) will be explained. Generally, in organic EL display, atransparent electrode, an organic luminescence layer and a metalelectrode are laminated on a transparent substrate in an orderconfiguring an illuminant (organic electro luminescence illuminant).Here, a organic luminescence layer is a laminated material of variousorganic thin films, and much compositions with various combination areknown, for example, a laminated material of hole injection layerincluding triphenylamine derivatives etc., a luminescence layerincluding fluorescent organic solids, such as anthracene; a laminatedmaterial of electronic injection layer including such a luminescencelayer and perylene derivatives, etc.; laminated material of these holeinjection layers, luminescence layer, and electronic injection layeretc.

An organic EL display emits light based on a principle that positivehole and electron are injected into an organic luminescence layer byimpressing voltage between a transparent electrode and a metalelectrode, the energy produced by recombination of these positive holesand electrons excites fluorescent substance, and subsequently light isemitted when excited fluorescent substance returns to ground state. Amechanism called recombination which takes place in an intermediateprocess is the same as a mechanism in common diodes, and, as isexpected, there is a strong non-linear relationship between electriccurrent and luminescence strength accompanied by rectification nature toapplied voltage.

In an organic EL display, in order to take out luminescence in anorganic luminescence layer, at least one electrode must be transparent.The transparent electrode usually formed with transparent electricconductor, such as indium tin oxide (ITO), is used as an anode. On theother hand, in order to make electronic injection easier and to increaseluminescence efficiency, it is important that a substance with smallwork function is used for cathode, and metal electrodes, such as Mg—Agand Al—Li, are usually used.

In organic EL display of such a configuration, an organic luminescencelayer is formed by a very thin film about 10 nm in thickness. For thisreason, light is transmitted nearly completely through organicluminescence layer as through transparent electrode. Consequently, sincethe light that enters, when light is not emitted, as incident light froma surface of a transparent substrate and is transmitted through atransparent electrode and an organic luminescence layer and then isreflected by a metal electrode, appears in front surface side of thetransparent substrate again, a display side of the organic EL displaylooks like mirror if viewed from outside.

In an organic EL display containing an organic electro luminescenceilluminant equipped with a transparent electrode on a surface side of anorganic luminescence layer that emits light by impression of voltage,and at the same time equipped with a metal electrode on a back side oforganic luminescence layer, a retardation plate may be installed betweenthese transparent electrodes and a polarization plate, while preparingthe polarization plate on the surface side of the transparent electrode.

Since the retardation plate and the polarization plate have functionpolarizing the light that has entered as incident light from outside andhas been reflected by the metal electrode, they have an effect of makingthe mirror surface of metal electrode not visible from outside by thepolarization action. If a retardation plate is configured with a quarterwavelength plate and the angle between the two polarization directionsof the polarization plate and the retardation plate is adjusted to π/4,the mirror surface of the metal electrode may be completely covered.

This means that only linearly polarized light component of the externallight that enters as incident light into this organic EL display istransmitted with the work of polarization plate. This linearly polarizedlight generally gives an elliptically polarized light by the retardationplate, and especially the retardation plate is a quarter wavelengthplate, and moreover when the angle between the two polarizationdirections of the polarization plate and the retardation plate isadjusted to π/4, it gives a circularly polarized light.

This circularly polarized light is transmitted through the transparentsubstrate, the transparent electrode and the organic thin film, and isreflected by the metal electrode, and then is transmitted through theorganic thin film, the transparent electrode and the transparentsubstrate again, and is turned into a linearly polarized light againwith the retardation plate. And since this linearly polarized light liesat right angles to the polarization direction of the polarization plate,it cannot be transmitted through the polarization plate. As the result,mirror surface of the metal electrode may be completely covered.

As described above, in order to block mirror reflection, the organic ELpanel of an organic EL display may use an elliptically or circularlypolarizing plate having a combination of a retardation plate and apolarizing plate with the pressure-sensitive adhesive layer interposedtherebetween. Alternatively, without an elliptically or circularlypolarizing plate directly bonded to an organic EL panel, a laminateformed by bonding an elliptically or circularly polarizing plate to atouch panel with the pressure-sensitive adhesive layer interposedtherebetween may be used in an organic EL panel.

The invention is applicable to various types of touch panel, such asoptical, ultrasonic, capacitance, and resistive touch panels. Aresistive touch panel includes: a touch-side, touch panel-formingelectrode plate having a transparent conductive thin film; and adisplay-side, touch panel-forming electrode plate having a transparentconductive thin film, wherein the electrode plates are opposed to eachother with spacers interposed therebetween in such a manner that thetransparent conductive thin films are opposed to each other. Acapacitance touch panel generally includes a transparent conductive filmthat has a transparent conductive thin film in a specific pattern and isformed over the surface of a display unit. The pressure-sensitiveadhesive optical film according to the invention may be used on any ofthe touch side and the display side.

EXAMPLES

Hereinafter, the invention is more specifically described with referenceto the examples, which however are not intended to limit the invention.In each example, “parts” and “%” are all by weight. Unless otherwisespecified below, the conditions for allowing standing at roomtemperature are 23° C. and 65% RH in all cases.

[Measurement of Weight Average Molecular Weight of (Meth)Acryl-BasedPolymer]

The weight average molecular weight and the degree of dispersion (weightaverage molecular weight/number average molecular weight) of each(meth)acryl-based polymer were determined using gel permeationchromatography (GPC).

Analyzer: HLC-8120GPC manufactured by TOSOH CORPORATION

Columns: GM7000H_(XL)+GMH_(XL)+GMH_(XL) manufactured by TOSOHCORPORATION

Column size: each 7.8 mmφ×30 cm, 90 cm in total

Column temperature: 40° C.

Flow rate: 0.8 ml/minute

Injection volume: 100 μl

Eluent: tetrahydrofuran

Detector: differential refractometer (RI)

Standard sample: polystyrene

[Haze]

The haze (%) of each transparent protective film was measured using ahaze meter (Model HM-150 manufactured by Murakami Color ResearchLaboratory).

[Viscosity Y of Pressure-Sensitive Adhesive Coating Liquid]

The viscosity Y (P) of each pressure-sensitive adhesive coating liquidwas measured using VISCOMETER Model BH manufactured by TOKI SANGYO CO.,LTD. under the following conditions.

Rotor: No. 4

Rotation speed: 20 rpm

Measurement temperature: 30° C.

[Thickness X of Pressure-Sensitive Adhesive Coating Liquid]

The thickness X (μm) of the pressure-sensitive adhesive coating liquidis the value calculated from the formula below using the solidconcentration (%) of the pressure-sensitive adhesive coating liquid andthe thickness (μm) of the pressure-sensitive adhesive layer formed byapplying the coating liquid and drying the applied liquid.

The thickness X (μm) of the pressure-sensitive adhesive coatingliquid={(the thickness (μm) of the pressure-sensitive adhesivelayer)/(the solid concentration (%) of the pressure-sensitive adhesivecoating liquid)}×100

<Preparation of Acrylic Pressure-Sensitive Adhesive (1)>

To a reaction vessel equipped with a condenser, a nitrogen-introducingtube, a thermometer, and a stirrer were added 99 parts of butylacrylate, 1 part of 4-hydroxybutyl acrylate, and 0.3 parts of2,2-azobisisobutyronitrile (based on 100 parts of the total solids ofthe monomers) together with ethyl acetate. Under a nitrogen gas stream,the mixture was allowed to react at 60° C. for 4 hours. Ethyl acetatewas then added to the reaction liquid, so that a solution containing anacryl-based polymer (A) with a weight average molecular weight of1,700,000 and a degree of dispersion of 4.1 was obtained (30% in solidconcentration). Based on 100 parts of the solid in the solutioncontaining the acryl-based polymer (A), 0.15 parts of trimethylolpropanexylylene diisocyanate (Takenate D110N manufactured by Mitsui TakedaChemicals, Inc.) and 0.2 parts of a silane coupling agent (A-100manufactured by Soken Chemical & Engineering Co., Ltd., an acetoacetylgroup-containing silane coupling agent) were added to the solution, sothat a solution of an acrylic pressure-sensitive adhesive (1) wasobtained.

<Preparation of Acrylic Pressure-Sensitive Adhesive (2)>

To a reaction vessel equipped with a condenser, a nitrogen-introducingtube, a thermometer, and a stirrer were added 94.9 parts of butylacrylate, 5 parts of acrylic acid, 0.1 parts of 2-hydroxyethyl acrylate,and 0.3 parts of dibenzoyl peroxide (based on 100 parts of the totalsolids of the monomers) together with ethyl acetate. Under a nitrogengas stream, the mixture was allowed to react at 60° C. for 7 hours.Ethyl acetate was then added to the reaction liquid, so that a solutioncontaining an acryl-based polymer (B) with a weight average molecularweight of 2,200,000 and a degree of dispersion of 3.9 was obtained (30%in solid concentration). Based on 100 parts of the solid in the solutioncontaining the acryl-based polymer (B), 0.6 parts of trimethylolpropanetolylene diisocyanate (CORONATE L manufactured by Nippon PolyurethaneIndustry Co., Ltd.) and 0.075 parts of γ-glycidoxypropylmethoxysilane(KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.) were added to thesolution, so that a solution of an acrylic pressure-sensitive adhesive(2) was obtained.

<Preparation of Acrylic Pressure-Sensitive Adhesive (3)>

To a reaction vessel equipped with a condenser, a nitrogen-introducingtube, a thermometer, and a stirrer were added 94.9 parts of butylacrylate, 5 parts of acrylic acid, 0.1 parts of 2-hydroxyethyl acrylate,and 0.3 parts of dibenzoyl peroxide (based on 100 parts of the totalsolids of the monomers) together with a mixed solvent of ethyl acetateand toluene whose weight ratio is 50 to 50. Under a nitrogen gas stream,the mixture was allowed to react at 60° C. for 7 hours. Ethyl acetatewas then added to the reaction liquid, so that a solution containing anacryl-based polymer (C) with a weight average molecular weight of500,000 and a degree of dispersion of 5 was obtained (50% in solidconcentration). Based on 100 parts of the solid in the solutioncontaining the acryl-based polymer (C), 0.6 parts of trimethylolpropanetolylene diisocyanate (CORONATE L manufactured by Nippon PolyurethaneIndustry Co., Ltd.) and 0.075 parts of γ-glycidoxypropylmethoxysilane(KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.) were added to thesolution, so that a solution of an acrylic pressure-sensitive adhesive(3) was obtained.

<Preparation of Acrylic Pressure-Sensitive Adhesive (4)>

To a reaction vessel equipped with a condenser, a nitrogen-introducingtube, a thermometer, and a stirrer were added 94.9 parts of butylacrylate, 5 parts of acrylic acid, 0.1 parts of 2-hydroxyethyl acrylate,and 0.3 parts of dibenzoyl peroxide (based on 100 parts of the totalsolids of the monomers) together with a mixed solvent of ethyl acetateand toluene whose weight ratio is 80 to 20. Under a nitrogen gas stream,the mixture was allowed to react at 60° C. for 7 hours. Ethyl acetatewas then added to the reaction liquid, so that a solution containing anacryl-based polymer (D) with a weight average molecular weight of1,000,000 and a degree of dispersion of 4 was obtained (50% in solidconcentration). Based on 100 parts of the solid in the solutioncontaining the acryl-based polymer (D), 0.6 parts of trimethylolpropanetolylene diisocyanate (CORONATE L manufactured by Nippon PolyurethaneIndustry Co., Ltd.) and 0.075 parts of γ-glycidoxypropylmethoxysilane(KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.) were added to thesolution, so that a solution of an acrylic pressure-sensitive adhesive(4) was obtained.

<Preparation of Acrylic Pressure-Sensitive Adhesive (5)>

To a reaction vessel equipped with a condenser, a nitrogen-introducingtube, a thermometer, and a stirrer were added 94.9 parts of butylacrylate, 5 parts of acrylic acid, 0.1 parts of 2-hydroxyethyl acrylate,and 0.3 parts of dibenzoyl peroxide (based on 100 parts of the totalsolids of the monomers) together with a mixed solvent of ethyl acetateand toluene whose weight ratio is 60 to 40. Under a nitrogen gas stream,the mixture was allowed to react at 60° C. for 7 hours. Ethyl acetatewas then added to the reaction liquid, so that a solution containing anacryl-based polymer (E) with a weight average molecular weight of700,000 and a degree of dispersion of 4.8 was obtained (50% in solidconcentration). Based on 100 parts of the solid in the solutioncontaining the acryl-based polymer (E), 0.6 parts of trimethylolpropanetolylene diisocyanate (CORONATE L manufactured by Nippon PolyurethaneIndustry Co., Ltd.) and 0.075 parts of γ-glycidoxypropylmethoxysilane(KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.) were added to thesolution, so that a solution of an acrylic pressure-sensitive adhesive(5) was obtained.

<Preparation of Acrylic Pressure-Sensitive Adhesive (6)>

To a vessel were added 980 parts of butyl acrylate and 20 parts ofacrylic acid, and they are mixed to form a monomer mixture.Subsequently, 20 parts of AQUALON HS-10 (manufactured by Dai-ichi KogyoSeiyaku Co., Ltd.) as a reactive surfactant and 635 parts ofion-exchanged water were added to 1,000 parts of the monomer mixtureprepared with the above composition, and forcedly emulsified by stirringat 6,000 (rpm) for 5 minutes using a homomixer (manufactured by PRIMIXCorporation), so that a monomer emulsion was obtained. To a reactionvessel equipped with a condenser, a nitrogen-introducing tube, athermometer, a dropping funnel, and a stirring blade were added 200parts of a portion of the monomer emulsion prepared as described aboveand 330 parts of ion-exchanged water. Subsequently, after the space inthe reaction vessel was sufficiently replaced with nitrogen gas, 0.6parts of ammonium persulfate was added to the vessel, and the mixturewas subjected to polymerization at 60° C. for 1 hour with stirring.Subsequently, 800 parts of the remaining portion of the monomer emulsionwas added dropwise to the reaction vessel over 3 hours, while thereaction vessel was kept at 60° C. The mixture was then subjected topolymerization for 3 hours, so that an aqueous dispersion containingemulsion particles of a (meth)acryl-based polymer (F) at a solidconcentration of 46.2% was obtained. Subsequently, after the aqueousdispersion was cooled to room temperature, 10% ammonia water was addedthereto, so that an aqueous dispersion with an adjusted pH of 8 and anadjusted solids content of 45.9% was obtained. The resulting dispersionwas used as an acrylic pressure-sensitive adhesive (6).

<Preparation of Acrylic Pressure-Sensitive Adhesive (7)>

Based on 100 parts of the solid in the solution containing theacryl-based polymer (A) prepared for the acrylic pressure-sensitiveadhesive (1), 0.3 parts of dibenzoyl peroxide (NYPER BMT manufactured byNOF CORPORATION), 0.02 parts of trimethylolpropane xylylene diisocyanate(Takenate D110N manufactured by Mitsui Takeda Chemicals, Inc.), and 0.2parts of a silane coupling agent (A-100 manufactured by Soken Chemical &Engineering Co., Ltd., an acetoacetyl group-containing silane couplingagent) were added to the solution, so that a solution of an acrylicpressure-sensitive adhesive (7) was obtained.

<Preparation of Acrylic Pressure-Sensitive Adhesive (8)>

To a reaction vessel equipped with a condenser, a nitrogen-introducingtube, a thermometer, and a stirrer were added 81.9 parts of butylacrylate, 13.0 parts of benzyl acrylate, 5.0 parts of acrylic acid, 0.1parts of 4-hydroxybutyl acrylate, and 0.1 parts of2,2′-azobisisobutyronitrile (based on 100 parts of the total solids ofthe monomers) together with ethyl acetate. Under a nitrogen gas stream,the mixture was allowed to react at 55° C. for 8 hours. Ethyl acetatewas then added to the reaction liquid, so that a solution containing anacryl-based polymer (G) with a weight average molecular weight of2,000,000 and a degree of dispersion of 3 was obtained (30% in solidconcentration). Based on 100 parts of the solid in the solutioncontaining the acryl-based polymer (G), 0.09 parts of dibenzoyl peroxide(NYPER BMT manufactured by NOF CORPORATION), 0.45 parts oftrimethylolpropane tolylene diisocyanate (CORONATE L manufactured byNippon Polyurethane Industry Co., Ltd.), 0.2 parts ofγ-glycidoxypropylmethoxysilane (KBM-403 manufactured by Shin-EtsuChemical Co., Ltd.), and 0.25 parts of a polyether compound (SilylSAT10, manufactured by Kaneka Corporation) were added to the solution,so that a solution of an acrylic pressure-sensitive adhesive (8) wasobtained.

<Preparation of Acrylic Pressure-Sensitive Adhesive (9)>

Based on 100 parts of the solid in the solution containing theacryl-based polymer (A) prepared for the acrylic pressure-sensitiveadhesive (1), 0.3 parts of dibenzoyl peroxide (NYPER BMT manufactured byNOF CORPORATION), 0.1 parts of trimethylolpropane xylylene diisocyanate(Takenate D110N manufactured by Mitsui Takeda Chemicals, Inc.), and 0.2parts of a silane coupling agent (A-100 manufactured by Soken Chemical &Engineering Co., Ltd., an acetoacetyl group-containing silane couplingagent) were added to the solution, so that a solution of an acrylicpressure-sensitive adhesive (9) was obtained.

<Preparation of Polarizer (1)>

An 80-μm-thick polyvinyl alcohol film was stretched to 3 times betweenrollers different in velocity ratio, while it was dyed in a 0.3% iodinesolution at 30° C. for 1 minute. The film was then stretched to a totalstretch ratio of 6 times, while it was immersed in an aqueous solutioncontaining 4% of boric acid and 10% of potassium iodide at 60° C. for0.5 minutes. Subsequently, the film was cleaned by immersion in anaqueous solution containing 1.5% of potassium iodide at 30° C. for 10seconds, and then dried at 50° C. for 4 minutes to give a 20-μm-thickpolarizer.

<Preparation of Polarizer (2)>

The thin high-performance polarizing film (5 μm in thickness) obtainedin Reference Production Example 1 described above was used.

<Preparation of Polarizer (3)>

The thin high-performance polarizing film (3 μm in thickness) obtainedin Reference Production Example 2 described above was used.

<Preparation of Polarizer (4)>

A process for forming a thin polarizing film was performed. In theprocess, a laminate including an amorphous PET substrate and a9-μm-thick PVA layer formed thereon was first subjected to auxiliaryin-air stretching at a stretching temperature of 130° C. to form astretched laminate. Subsequently, the stretched laminate was subjectedto dyeing to form a colored laminate, and the colored laminate wassubjected to stretching in an aqueous boric acid solution at astretching temperature of 65° C. to a total stretch ratio of 5.94 times,so that an optical film laminate was obtained, which had a 4-μm-thickPVA layer stretched together with the amorphous PET substrate. Suchtwo-stage stretching successfully formed an optical film laminate havinga 4-μm-thick PVA layer, which was produced on the amorphous PETsubstrate, contained highly oriented PVA molecules, and formed ahighly-functional polarizing film in which iodine adsorbed by the dyeingformed a polyiodide ion complex oriented highly in a single direction.

(Transparent Protective Films)

The following transparent protective films were used. The symbols inTables 1 and 2 represent the following materials, respectively.

40TAC: A 40-μm-thick triacetylcellulose film (KC4UY manufactured byKonica Minolta Holdings, Inc., 0.3% in haze value)

80TAC: An 80-μm-thick triacetylcellulose film (TD80UL manufactured byFujifilm Corporation, 0.3% in haze value)

20ACRYL: A 20-μm-thick acrylic resin film (0.2% in haze value)

22ZEONOR: A 22-μm-thick cyclic olefin-based resin film (ZEONOR ZD12manufactured by ZEON CORPORATION, 0.1% in haze value)

40APET: A 40-μm-thick amorphous polyethylene terephthalate film(NOVACLEAR manufactured by Mitsubishi Plastics, Inc., 0.2% in hazevalue)

(Retardation Plates)

The following retardation plates were used. The symbols in Table 2represent the following materials, respectively.

50POLYCA: A 50-μm-thick polycarbonate film (PURE-ACE WR manufactured byTEIJIN LIMITED., 147 nm in retardation)

34OLEFIN: A 34-μm-thick cyclic olefin-based resin film (a filmmanufactured by Kaneka Corporation, 140 nm in retardation)

33OLEFIN: A 33-μm-thick cyclic olefin-based resin film (a filmmanufactured by Kaneka Corporation, 270 nm in retardation)

(Optical Films)

The following optical films were used. The symbols in Table 3 representthe following materials, respectively.

40TAC: A 40-μm-thick triacetylcellulose film (KC4UY manufactured byKonica Minolta Holdings, Inc., 0.3% in haze value)

60TAC: A 60-μm-thick triacetylcellulose film (TD60UL manufactured byFujifilm Corporation, 0.3% in haze value)

80TAC: An 80-μm-thick triacetylcellulose film (TD80UL manufactured byFujifilm Corporation, 0.3% in haze value)

30ACRYL: A 30-μm-thick acrylic resin film (0.2% in haze value)

In Table 3, 40TAC:*1 represents an antiglare hard coat film prepared bythe method described below. In Table 3, 40TAC:*2 represents anantireflection film (DSG-03 (trade name) manufactured by Dai NipponPrinting Co., Ltd.).

(Preparation of Antiglare Hard Coat Film)

A hard coat layer-forming material (OPSTAR Z7540 (trade name)manufactured by JSR Corporation, solids content: 56% by weight, solvent:butyl acetate/methyl ethyl ketone (MEK)=76/24 (in weight ratio)) wasprovided, which was a dispersion containing silica nanoparticlesproduced by coupling inorganic oxide particles with a polymerizableunsaturated group-containing organic compound. The hard coatlayer-forming material contains components (A): dipentaerythritol andisophorone diisocyanate-based polyurethane and component (B): silicafine particles whose surface is modified with an organic molecule (100nm or less in weight average particle size), in which the ratio of thetotal weight of components (A) to the weight of component (B) is 2:3.Based on 100 parts by weight of the resin solid in the hard coatlayer-forming material, 5 parts by weight of acryl-styrene crosslinkedfine particles (TECHNOPOLYMER XX80AA (trade name) manufactured bySEKISUI CHEMICAL CO., LTD., weight average particle size: 5.5 μm,refractive index: 1.515), 0.1 parts by weight of a leveling agent(GRANDIC PC-4100 (trade name) manufactured by DIC Corporation), and 0.5parts by weight of a photopolymerization initiator (Irgacure 127 (tradename) manufactured by Ciba Specialty Chemicals Inc.) were added to thehard coat layer-forming material. The resulting mixture was diluted withbutyl acetate/MEK (2/1 in weight ratio) to a solid concentration of 45%by weight, so that an antiglare hard coat layer-forming material wasobtained.

A triacetylcellulose film (KC4UY (trade name) manufactured by KonicaMinolta Holdings, Inc., 40 μm in thickness) was provided as atransparent plastic film substrate. The antiglare hard coatlayer-forming material was applied to one side of the transparentplastic film substrate using a comma coater to form a coating film. Thecoating film was then dried by heating at 100° C. for 1 minute.Subsequently, the coating film was cured by ultraviolet irradiation at atotal dose of 300 mJ/cm² using a high-pressure mercury lamp to form a9-μm-thick antiglare hard coat layer, so that an antiglare hard coatfilm was obtained.

Example 1 Preparation of Polarizing Plate

A polarizing plate was prepared by bonding 40-μm-thicktriacetylcellulose films (KC4UY manufactured by Konica Minolta Holdings,Inc., 0.3% in haze value) as first and second transparent protectivefilms to both sides of the polarizer (1) with an polyvinyl alcohol-basedadhesive.

(Preparation of Pressure-Sensitive Adhesive Coating Liquid)

The solution of the acrylic pressure-sensitive adhesive (1) prepared inProduction Example 1 was diluted with ethyl acetate to a solidconcentration of 15%, so that a pressure-sensitive adhesive coatingliquid was obtained. The pressure-sensitive adhesive coating liquid hada viscosity of 65 P.

(Preparation of Pressure-Sensitive Adhesive Polarizing Plate)

The pressure-sensitive adhesive coating liquid prepared as describedabove was applied to one side of a 38-μm-thick, silicone-treated,polyethylene terephthalate (PET) film (MRF38 manufactured by MitsubishiPolyester Film) with a fountain die coater so as to form a coating witha thickness of 134.0 μm. The coating was then dried at 155° C. for 1minute to form a 20-μm-thick pressure-sensitive adhesive layer. Thepressure-sensitive adhesive layer was transferred to the secondtransparent protective film side of the polarizing plate prepared asdescribed above, so that a pressure-sensitive adhesive polarizing platewas obtained.

Examples 2 to 29 and Comparative Examples 1 to 4

Pressure-sensitive adhesive polarizing plates were prepared as inExample 1, except that the polarizing plates used were each producedwith the polarizer and the first and second transparent protective filmsshown in Table 1, the pressure-sensitive adhesive coating liquid shownin Table 1 was used, the coating thickness of the pressure-sensitiveadhesive coating liquid was changed as shown in Table 1, and thethickness of the pressure-sensitive adhesive layer was changed as shownin Table 1. When the polarizer (2), (3), or (4) was used, the polarizingplate was prepared as follows. The first transparent protective film wasbonded to the resulting laminate film or the resulting optical filmlaminate with a polyvinyl alcohol-based adhesive being applied to thesurface of the polarizing film of the laminate film or the optical filmlaminate. Subsequently, the amorphous PET substrate was peeled off, andthe second transparent protective film was bonded to the product with apolyvinyl alcohol-based adhesive, so that the polarizing plate wasobtained. When the second transparent protective film was not used inthe polarizing plate, the pressure-sensitive adhesive layer wastransferred to the polarizing film to form the pressure-sensitiveadhesive polarizing plate.

Examples 30 to 37 and Comparative Examples 5 to 8

Pressure-sensitive adhesive polarizing plates were prepared as inExample 1, except that the polarizing plates used were each producedwith the polarizer and the first and second transparent protective filmsshown in Table 2, the pressure-sensitive adhesive coating liquid shownin Table 2 was used, the coating thickness of the pressure-sensitiveadhesive coating liquid was changed as shown in Table 2, and thethickness of the pressure-sensitive adhesive layer was changed as shownin Table 2. The pressure-sensitive adhesive layer bonded to thepolarizing plate corresponds to the first pressure-sensitive adhesivelayer in Table 2.

The structure shown in each of FIGS. 4 to 7 was further obtained usingthe resulting pressure-sensitive adhesive polarizing plate. The firstretardation plate was bonded to the pressure-sensitive adhesivepolarizing plate with the second pressure-sensitive adhesive layer, andthe second retardation plate was bonded to the pressure-sensitiveadhesive polarizing plate with the third pressure-sensitive adhesivelayer, when the laminated pressure-sensitive adhesive polarizing plateswere obtained. The second and third pressure-sensitive adhesive layerswere each formed as follows. The pressure-sensitive adhesive coatingliquid shown in Table 2 was applied to one side of a 38-μm-thick,silicone-treated, polyethylene terephthalate (PET) film (MRF38manufactured by Mitsubishi Polyester Film) with a fountain die coater soas to form a coating with the thickness shown in Table 2. The coatingwas then dried at 155° C. for 1 minute to form a pressure-sensitiveadhesive layer with the thickness shown in Table 2. The resulting secondor third pressure-sensitive adhesive layer was transferred to the firstor second retardation plate to form a pressure-sensitive adhesiveretardation plate, which was used to form the laminatedpressure-sensitive adhesive polarizing plate.

Examples 38 to 52 and Comparative Examples 9 to 13

Pressure-sensitive adhesive optical films were prepared as in Example 1,except that the optical film shown in Table 3 was used instead of thepolarizing plate in the preparation of the pressure-sensitive adhesivepolarizing plate, the pressure-sensitive adhesive coating liquid shownin Table 3 was used, the coating thickness of the pressure-sensitiveadhesive coating liquid was changed as shown in Table 3, and thethickness of the pressure-sensitive adhesive layer was changed as shownin Table 3.

In each example, the pressure-sensitive adhesive coating liquid wasprepared as follows. The acrylic pressure-sensitive adhesive was dilutedwith ethyl acetate (for a solution) or with water (for an aqueousdispersion) when the solid concentration and viscosity of thepressure-sensitive adhesive coating liquid were adjusted. When thepolarizing plate did not have the second transparent protective film,the pressure-sensitive adhesive layer was transferred to a side of thepolarizing plate opposite to a side where the first transparentprotective film was provided (namely, transferred directly to thepolarizer).

The pressure-sensitive adhesive polarizing plates, the laminatedpressure-sensitive adhesive polarizing plates, and thepressure-sensitive adhesive optical films (the samples) obtained in theexamples and the comparative examples were evaluated as described below.The evaluation results are shown in Tables 1 to 3.

<Thickness of Pressure-Sensitive Adhesive Layer and Standard Deviation>

The thickness of each pressure-sensitive adhesive layer in 5 cm squarepiece of each pressure-sensitive adhesive polarizing plate, laminatedpressure-sensitive adhesive polarizing plate, or pressure-sensitiveadhesive optical film (sample) was measured at 2,061 points at intervalsof 1 mm by optical interferometry at a wavelength of 700 to 900 nm usinga spectrophotometer MCPD-3700 manufactured by Otsuka Electronics Co.,Ltd. The thickness of the pressure-sensitive adhesive layer and thethickness (μm) standard deviation were calculated from the measuredvalues.

<Measurement of ISC>

The level of the in-plane irregularities of each pressure-sensitiveadhesive polarizing plate, laminated pressure-sensitive adhesivepolarizing plate, or pressure-sensitive adhesive optical film wasdetermined as an ISC value using EyeScale-4W manufactured by I SystemCo., Ltd. in the ISC measurement mode of the 3CCD image sensor accordingto the operation manual of the system.

(Measurement Conditions)

The sample used was a laminate of a non-alkali glass plate (1737manufactured by Corning Incorporated) and the pressure-sensitiveadhesive polarizing plate, the laminated pressure-sensitive adhesivepolarizing plate, or the pressure-sensitive adhesive optical film bondedto the glass plate. The light source, the sample, and the screen wereplaced in this order, and the transmission image of the sample projectedon the screen was measured with the CCD camera. The sample (thepressure-sensitive adhesive layer bonded to the non-alkali glass plate)was placed 30 cm apart from the light source and the CCD camera. Thescreen was placed 100 cm apart from the light source and the CCD camera.The light source and the CCD camera were placed 20 cm apart equally fromthe sample and the screen.

The ISC value is an index for the evaluation of irregularities. An ISCvalue of 100 or less indicates that irregularities are controlled to below. The lower ISC value indicates the lower level of irregularities.The ISC value is preferably 70 or less, and more preferably 50 or less.

<Visual Evaluation of Pressure-Sensitive Adhesive Polarizing Plate andLaminated Pressure-Sensitive Adhesive Polarizing Plate>

The pressure-sensitive adhesive polarizing plate or laminatedpressure-sensitive adhesive polarizing plate (sample) was bonded to ablack acrylic plate, and the appearance of it was visually evaluatedunder a fluorescent light according to the criteria below. Concerningthe laminated pressure-sensitive adhesive polarizing plate, the firstpressure-sensitive adhesive layer was used to form thepressure-sensitive adhesive polarizing plate, the secondpressure-sensitive adhesive layer was used to form thepressure-sensitive adhesive retardation plate having the firstretardation plate, and the third pressure-sensitive adhesive layer wasused to form the pressure-sensitive adhesive retardation plate havingthe second retardation plate, when the samples were formed.

OOO: Unevenness is not observed at all.

OO: Unevenness is hardly observed.

O: Unevenness is observed but not significant.

X: Unevenness is observed.

<Visual Evaluation of Pressure-Sensitive Adhesive Optical Film>

The pressure-sensitive adhesive optical film (sample) was bonded to atransparent acrylic plate with a smooth surface, which was intended torepresent a structure including a front face plate and an optical filmbonded to the viewer side of the front faceplate. The appearance of theresulting laminate was visually evaluated under a fluorescent lightaccording to the criteria below. For the evaluation, the optical filmside and the acrylic plate side were observed, respectively.

OOO: Surface irregularities are not observed at all.

OO: Surface irregularities are hardly observed.

O: Surface irregularities are observed but have no significant effect onvisibility.

X: Surface irregularities are large and have a significant effect onvisibility.

TABLE 1 Pressure-sensitive adhesive layer Polarizing platePressure-sensitive adhesive Pressure-sensitive Evaluations Second Weightadhesive coating liquid Pressure-senstiive transparent average CoatingCoating adhesive layer Polarizer First transparent protectiveAcryl-based molecular Solid liquid liquid Standard Unevenness Thicknessprotective film film polymer weight Degree of concentration viscositythickness Thickness deviation ISC Visual Type (μm) Type Haze (%) TypeType type (×10,000) dispersion (%) Y (P) X (μm) 0.8X − Y (μm) (μm) valuecheck Example 1 (1) 20 40TAC 0.3 40TAC (1) A 170 4.1 15 65 134.0 42.220.1 0.10 71 ◯ Example 2 (1) 20 40TAC 0.3 40TAC (9) A 170 4.1 14 50144.3 65.4 20.2 0.10 90 ◯ Example 3 (1) 20 40TAC 0.3 40TAC (2) B 220 3.912 88 191.7 65.3 23.0 0.10 65 ◯◯ Example 4 (1) 20 40TAC 0.3 40TAC (2) B220 3.9 11 50 136.4 59.1 15.0 0.04 59 ◯◯ Example 5 (1) 20 40TAC 0.340TAC (2) B 220 3.9 13 132 176.9 9.5 23.0 0.06 45 ◯◯◯ Example 6 (1) 2040TAC 0.3 40TAC (3) C 50 5 29 44 80.0 20.0 23.2 0.03 23 ◯◯◯ Example 7(1) 20 40TAC 0.3 40TAC (4) D 100 4 21 50 110.0 38.0 23.1 0.03 25 ◯◯◯Example 8 (1) 20 40TAC 0.3 40TAC (5) E 70 4.8 30 25 99.7 54.7 29.9 0.0531 ◯◯◯ Example 9 (1) 20 80TAC 0.3 40TAC (4) D 100 4 21 50 110.0 38.023.1 0.03 38 ◯◯◯ Example 10 (1) 20 40TAC 0.3 80TAC (4) D 100 4 21 50110.5 38.4 23.2 0.03 40 ◯◯◯ Example 11 (1) 20 40TAC 0.3 20ACRYL (4) D100 4 21 50 110.0 38.0 23.1 0.03 23 ◯◯◯ Example 12 (1) 20 20ACRYL 0.222ZEONOR (4) D 100 4 21 50 110.0 38.0 23.1 0.03 20 ◯◯◯ Example 13 (1) 2080TAC 0.3 80TAC (4) D 100 4 21 50 109.5 37.6 23.0 0.03 98 ◯ Example 14(1) 20 40TAC 0.3 40TAC (4) D 100 4 21 50 110.5 38.4 23.2 0.03 23 ◯◯◯Example 15 (1) 20 40TAC 0.3 40TAC (4) D 100 4 21 50 109.0 37.2 22.9 0.0330 ◯◯◯ Example 16 (1) 20 40TAC 0.3 40TAC (4) D 100 4 21 50 110.0 38.023.1 0.03 42 ◯◯◯ Example 17 (1) 20 40TAC 0.3 40TAC (6) F — — 38 10 52.431.9 19.9 0.03 24 ◯◯◯ Example 18 (2) 5 40TAC 0.3 40APET (2) B 220 3.9 1150 135.5 58.4 14.9 0.07 50 ◯◯◯ Example 19 (3) 3 40TAC 0.3 40APET (2) B220 3.9 11 50 135.5 58.4 14.9 0.07 47 ◯◯◯ Example 20 (3) 3 40TAC 0.3 —(2) B 220 3.9 11 50 137.3 59.8 15.1 0.07 45 ◯◯◯ Example 21 (2) 5 40TAC0.3 40APET (9) A 170 4.1 14 50 142.9 64.3 20.0 0.07 45 ◯◯◯ Example 22(3) 3 40TAC 0.3 40APET (9) A 170 4.1 14 50 143.6 64.9 20.1 0.07 43 ◯◯◯Example 23 (3) 3 40TAC 0.3 — (9) A 170 4.1 14 50 142.9 64.3 20.0 0.07 40◯◯◯ Example 24 (2) 5 40TAC 0.3 40APET (4) D 100 4 21 50 110.0 38.0 23.10.03 22 ◯◯◯ Example 25 (3) 3 40TAC 0.3 40APET (4) D 100 4 21 50 110.538.4 23.2 0.03 20 ◯◯◯ Example 26 (3) 3 40TAC 0.3 — (4) D 100 4 21 50109.0 37.2 22.9 0.03 15 ◯◯◯ Example 27 (4) 4 40TAC 0.3 — (2) B 220 3.911 50 135.5 58.4 14.9 0.07 45 ◯◯◯ Example 28 (4) 4 40TAC 0.3 — (9) A 1704.1 14 50 142.9 64.3 20.0 0.07 35 ◯◯◯ Example 29 (4) 4 40TAC 0.3 — (4) D100 4 21 50 110.0 38.0 23.1 0.03 15 ◯◯◯ Comparative (1) 20 40TAC 0.340TAC (7) A 170 4.1 13 35 162.3 94.8 21.1 0.14 107 X Example 1Comparative (1) 20 40TAC 0.3 40TAC (8) G 200 3 13 50 181.5 95.2 23.60.17 140 X Example 2 Comparative (1) 20 40TAC 0.3 40TAC (9) A 170 4.1 1335 153.8 88.1 20.0 0.14 108 X Example 3 Comparative (1) 20 40TAC 0.340TAC (2) B 220 3.9 11 50 210.9 118.7 23.2 0.13 118 X Example 4

TABLE 2 Polarizing plate Pressure-sensitive adhesive layer FirstPressure-sensitive adhesive transparent Second Retardation plate WeightPolarizer protective transparent First Second Acryl- average Thick- filmprotective Retardation retardation based molecular ness Haze film plateplate polymer weight Degree of Type (μm) Type (%) Type Type Type TypeType type (×10,000) dispersion Example 30 (1) 20 40TAC 0.3 40TAC50POLYCA — First (9) A 170 4.1 pressure-sensitive adhesive layer Second(4) D 100 4.0 pressure-sensitive adhesive layer Example 31 (1) 20 40TAC0.3 40TAC 34OLEFIN 33OLEFIN First (9) A 170 4.1 pressure-sensitiveadhesive layer Second (9) A 170 4.1 pressure-sensitive adhesive layerThird (4) D 100 4.0 pressure-sensitive adhesive layer Example 32 (3) 340TAC 0.3 — 50POLYCA — First (9) A 170 4.1 pressure-sensitive adhesivelayer Second (4) D 100 4.0 pressure-sensitive adhesive layer Example 33(3) 3 40TAC 0.3 — 34OLEFIN 33OLEFIN First (9) A 170 4.1pressure-sensitive adhesive layer Second (9) A 170 4.1pressure-sensitive adhesive layer Third (4) D 100 4.0 pressure-sensitiveadhesive layer Example 34 (3) 3 40TAC 0.3 — 50POLYCA — First (2) B 2203.9 pressure-sensitive adhesive layer Second (2) B 220 3.9pressure-sensitive adhesive layer Example 35 (4) 4 40TAC 0.3 — 50POLYCA— First (9) A 170 4.1 pressure-sensitive adhesive layer Second (4) D 1004.0 pressure-sensitive adhesive layer Example 36 (4) 4 40TAC 0.3 —34OLEFIN 33OLEFIN First (9) A 170 4.1 pressure-sensitive adhesive layerSecond (9) A 170 4.1 pressure-sensitive adhesive layer Third (4) D 1004.0 pressure-sensitive adhesive layer Example 37 (4) 4 40TAC 0.3 —50POLYCA First (2) B 220 3.9 pressure-sensitive adhesive layer Second(2) B 220 3.9 pressure-sensitive adhesive layer Comparative (1) 20 40TAC0.3 40TAC 50POLYCA — First (2) B 220 3.9 Example 5 pressure-sensitiveadhesive layer Second (2) B 220 3.9 pressure-sensitive adhesive layerComparative (1) 20 40TAC 0.3 40TAC 34OLEFIN 33OLEFIN First (2) B 220 3.9Example 6 pressure-sensitive adhesive layer Second (2) B 220 3.9pressure-sensitive adhesive layer Third (2) B 220 3.9 pressure-sensitiveadhesive layer Comparative (3) 3 40TAC 0.3 — 50POLYCA — First (2) B 2203.9 Example 7 pressure-sensitive adhesive layer Second (2) B 220 3.9pressure-sensitive adhesive layer Comparative (3) 3 40TAC 0.3 — 34OLEFIN33OLEFIN First (2) B 220 3.9 Example 8 pressure-sensitive adhesive layerSecond (2) B 220 3.9 pressure-sensitive adhesive layer Third (2) B 2203.9 pressure-sensitive adhesive layer Pressure-sensitive adhesive layerPressure-sensitive Evaluations adhesive coating liquid Pressure-senstiveCoating Coating adhesive layer Solid liquid liquid Standard Unevennessconcentration viscosity thickness Thickness deviation ISC Visual (%) Y(P) X (μm) 0.8X − Y (μm) (μm) value check Example 30 14 50 85.7 18.612.0 0.05 62 ◯◯ 21 50 71.4 7.1 15.0 0.02 ◯◯ Example 31 14 50 85.7 18.612.0 0.05 65 ◯◯ 14 50 35.7 −21.4 5.0 0.05 ◯◯ 21 50 71.4 7.1 15.0 0.02 ◯◯Example 32 14 50 85.7 18.6 12.0 0.05 27 ◯◯◯ 21 50 71.4 7.1 15.0 0.02 ◯◯◯Example 33 14 50 85.7 18.6 12.0 0.05 30 ◯◯◯ 14 50 35.7 −21.4 5.0 0.05◯◯◯ 21 50 71.4 7.1 15.0 0.02 ◯◯◯ Example 34 11 50 109.1 37.3 12.0 0.0983 ◯ 11 50 136.4 59.1 15.0 0.10 ◯ Example 35 14 50 85.7 18.6 12.0 0.0522 ◯◯◯ 21 50 71.4 7.1 15.0 0.02 ◯◯◯ Example 36 14 50 85.7 18.6 12.0 0.0525 ◯◯◯ 14 50 35.7 −21.4 5.0 0.05 ◯◯◯ 21 50 71.4 7.1 15.0 0.02 ◯◯◯Example 37 11 50 109.1 37.3 12.0 0.09 70 ◯ 11 50 136.4 59.1 15.0 0.10 ◯Comparative 11 50 181.8 95.5 20.0 0.13 122 X Example 5 11 50 209.1 117.323.0 0.14 X Comparative 11 50 181.8 95.5 20.0 0.13 132 X Example 6 11 50181.8 95.5 20.0 0.13 X 11 50 209.1 117.3 23.0 0.14 X Comparative 11 50181.8 95.5 20.0 0.13 111 X Example 7 11 50 209.1 117.3 23.0 0.14 XComparative 11 50 181.8 95.5 20.0 0.13 115 X Example 8 11 50 181.8 95.520.0 0.13 X 11 50 209.1 117.3 23.0 0.14 X

TABLE 3 Pressure-sensitive adhesive layer Pressure-sensitive adhesiveWeight average Optical film Acryl-based molecular Thickness HazeReflectance polymer weight Degree of Type (μm) (%) (%) Remark Type type(×10,000) dispersion Example 38 40TAC 40 0.3 4.1 — (1) A 170 4.1 Example39 40TAC 40 0.3 4.1 — (9) A 170 4.1 Example 40 40TAC 40 0.3 4.1 — (2) B220 3.9 Example 41 40TAC 40 0.3 4.1 — (2) B 220 3.9 Example 42 40TAC 400.3 4.1 — (2) B 220 3.9 Example 43 40TAC 40 0.3 4.1 — (3) C  70 5Example 44 40TAC 40 0.3 4.1 — (4) D 100 4 Example 45 40TAC 40 0.3 4.1 —(5) E  50 4.8 Example 46 40TAC 40 0.3 4.1 — (6) F — — Example 47 80TAC80 0.3 4.0 — (4) D 100 4 Example 48 60TAC 60 0.3 4.0 — (4) D 100 4Example 49 40TAC 40 0.3 4.1 — (4) D 100 4 Example 50 30ACRYL 30 0.2 4.0— (4) D 100 4 Example 51 40TAC 40 14 — *1 (4) D 100 4 Example 52 40TAC40 0.3 1.1 *2 (4) D 100 4 Comparative 40TAC 40 0.3 4.1 — (2) B 220 3.9Example 9 Comparative 80TAC 80 0.3 4.0 — (2) B 220 3.9 Example 10Comparative 40TAC 40 0.3 4.1 — (8) G 200 3 Example 11 Comparative 40TAC40 0.3 4.1 — (7) A 170 4.1 Example 12 Comparative 40TAC 40 0.3 4.1 — (9)A 170 4.1 Example 13 Pressure-sensitive adhesive layerPressure-sensitive Evaluations adhesive coating Unevenness liquidPressure-sensttive Visual check Solid Coating Coating adhesive layerVisual check (observation concen- liquid liquid Standard (observationthrough tration viscosity thickness Thickness deviation ISC from filmacrylic (%) Y (P) X (μm) 0.8X-Y (μm) (μm) value side) plate) Example 3815 65 134.0 42.2 20.1 0.10 60 ◯◯ ◯◯ Example 39 14 50 144.3 65.4 20.20.10 80 ◯ ◯ Example 40 12 88 191.7 65.3 23.0 0.10 55 ◯◯ — Example 41 1150 136.4 59.1 15.0 0.04 50 ◯◯ ◯◯ Example 42 13 132 176.9 9.5 23.0 0.0635 ◯◯◯ — Example 43 29 44 80.0 20.0 23.2 0.03 20 ◯◯◯ — Example 44 21 50110.0 38.0 23.1 0.03 25 ◯◯◯ — Example 45 30 25 99.7 54.7 29.9 0.05 30◯◯◯ — Example 46 38 10 60.8 38.6 23.1 0.03 20 ◯◯◯ ◯◯◯ Example 47 21 50110.0 38.0 23.1 0.03 52 ◯◯ ◯◯ Example 48 21 50 110.0 38.0 23.1 0.03 45◯◯ ◯◯ Example 49 21 50 110.0 38.0 23.1 0.03 25 ◯◯◯ ◯◯◯ Example 50 21 50110.0 38.0 23.1 0.03 20 ◯◯◯ ◯◯◯ Example 51 21 50 110.0 38.0 23.1 0.03 20◯◯◯ ◯◯◯ Example 52 21 50 110.0 38.0 23.1 0.03 20 ◯◯◯ ◯◯◯ Comparative 1150 210.9 118.7 23.2 0.13 110 X X Example 9 Comparative 11 50 210.9 118.723.2 0.13 130 X X Example 10 Comparative 13 50 181.5 95.2 23.6 0.17 120X X Example 11 Comparative 13 35 162.3 94.8 21.1 0.14 100 X X Example 12Comparative 13 35 153.8 88.1 20.0 0.14 90 X X Example 13

DESCRIPTION OF REFERENCE SIGNS

-   1 Optical film-   2 Pressure-sensitive adhesive layer-   A Polarizing plate-   B Retardation plate-   C Surface treatment film-   a Polarizer-   b1 First transparent protective film-   b2 Second transparent protective film-   10 Thin high-performance polarizing film-   11 Resin substrate-   12 PVA-type resin layer-   13 Laminate film-   14 Dyeing solution containing dichroic material 14′-   15 Aqueous boric acid solution-   16 Roll type stretching apparatus having a plurality of sets of    rollers different in circumferential speed-   (A) Manufacturing process of laminate film including resin substrate    and PVA resin layer-   (B) Dyeing process-   (C) Crosslinking process-   (D) Stretching process-   (E) Crosslinking process before dyeing process-   (F) Crosslinking process before stretching process (D)-   (G) Cleaning process-   (H) Drying process-   (I) Transferring process

1-23. (canceled)
 24. A method for producing a pressure-sensitiveadhesive optical film comprising an optical film and apressure-sensitive adhesive layer provided on the optical film, themethod comprising the steps of: (1A) applying a pressure-sensitiveadhesive coating liquid with a viscosity Y (P) to the optical film toform a coating with a thickness X (μm); and (2A) drying the appliedpressure-sensitive adhesive coating liquid to form a pressure-sensitiveadhesive layer, wherein the viscosity Y of the pressure-sensitiveadhesive coating liquid and the thickness X of the coating satisfy therelation 0.8X−Y≦68, the pressure-sensitive adhesive layer has athickness (μm) standard deviation of 0.12 μm or less.
 25. A method forproducing a pressure-sensitive adhesive optical film comprising anoptical film and a pressure-sensitive adhesive layer provided on theoptical film, the method comprising the steps of: (1B) applying apressure-sensitive adhesive coating liquid with a viscosity Y (P) to arelease film to form a coating with a thickness X (μm); (2B) drying theapplied pressure-sensitive adhesive coating liquid to form apressure-sensitive adhesive layer; and (3) bonding thepressure-sensitive adhesive layer, which is formed on the release film,to the optical film, wherein the viscosity Y of the pressure-sensitiveadhesive coating liquid and the thickness X of the coating satisfy therelation 0.8X−Y≦68, the pressure-sensitive adhesive layer has athickness (μm) standard deviation of 0.12 μm or less.
 26. The method forproducing a pressure-sensitive adhesive optical film according to claim24, wherein the optical film is a polarizing plate comprising apolarizer and a first transparent protective film provided on one sideof the polarizer or first and second transparent protective filmsprovided on both sides of the polarizer, the first transparentprotective film has a haze value of 15% or less, and thepressure-sensitive adhesive layer is provided on a side of thepolarizing plate opposite to a side where the first transparentprotective film is provided.
 27. The method for producing apressure-sensitive adhesive optical film according to claim 26, whereinthe first transparent protective film has a thickness of 60 μm or less.28. The method for producing a pressure-sensitive adhesive optical filmaccording to claim 26, wherein the polarizing plate has first and secondtransparent protective films on both sides of the polarizer, and atleast one of the first and second transparent protective films has athickness of 60 μm or less.
 29. The method for producing apressure-sensitive adhesive optical film according to claim 26, whereinthe polarizer has a thickness of 10 μm or less.
 30. The method forproducing a pressure-sensitive adhesive optical film according to claim24, wherein the optical film is a retardation plate.
 31. The method forproducing a pressure-sensitive adhesive optical film according to claim30, wherein the retardation plate has a thickness of 60 μm or less. 32.The method for producing a pressure-sensitive adhesive optical filmaccording to claim 24, wherein the optical film has a haze value of 15%or less.
 33. The method for producing a pressure-sensitive adhesiveoptical film according to claim 32, wherein the optical film is intendedto be bonded to a front face plate or a touch panel.
 34. The method forproducing a pressure-sensitive adhesive optical film according to claim32, wherein the optical film has a thickness of 60 μm or less.
 35. Themethod for producing a pressure-sensitive adhesive optical filmaccording to claim 32, wherein the optical film is a surface treatmentfilm.
 36. The method for producing a pressure-sensitive adhesive opticalfilm according to claim 24, wherein the pressure-sensitive adhesivecoating liquid has a viscosity Y (P) of 2 to 160 P, and the coating hasa thickness X (μm) of 20 to 250 μm.
 37. A method for producing apressure-sensitive adhesive optical film comprising at least two opticalfilms and at least two pressure-sensitive adhesive layers alternatelylaminated, the method comprising the steps of: (1A) applying apressure-sensitive adhesive coating liquid with a viscosity Y (P) to atleast one of the optical film to form a coating with a thickness X (μm);and (2A) drying the applied pressure-sensitive adhesive coating liquidto form a pressure-sensitive adhesive layer, wherein the viscosity Y ofthe pressure-sensitive adhesive coating liquid and the thickness X ofthe coating satisfy the relation 0.8X−Y≦68, at least one of thepressure-sensitive adhesive layer has a thickness (μm) standarddeviation of 0.12 μm or less.
 38. A method for producing apressure-sensitive adhesive optical film comprising at least two opticalfilms and at least two pressure-sensitive adhesive layers alternatelylaminated, the method comprising the steps of: (1B) applying apressure-sensitive adhesive coating liquid with a viscosity Y (P) to arelease film to form a coating with a thickness X (μm); (2B) drying theapplied pressure-sensitive adhesive coating liquid to form apressure-sensitive adhesive layer; and (3) bonding thepressure-sensitive adhesive layer, which is formed on the release film,to at least one of the optical film, wherein the viscosity Y of thepressure-sensitive adhesive coating liquid and the thickness X of thecoating satisfy the relation 0.8X−Y≦68, at least one of thepressure-sensitive adhesive layer has a thickness (μm) standarddeviation of 0.12 μm or less.
 39. The method for producing apressure-sensitive adhesive optical film according to claim 37, whereineach of the at least two pressure-sensitive adhesive layers has athickness (μm) standard deviation of 0.12 μm or less.
 40. The method forproducing a pressure-sensitive adhesive optical film according to claim37, wherein one of the optical films is a polarizing plate comprising apolarizer and a first transparent protective film provided on one sideof the polarizer or first and second transparent protective filmsprovided on both sides of the polarizer, the first transparentprotective film has a haze value of 15% or less, and thepressure-sensitive adhesive layer is provided on a side of thepolarizing plate opposite to a side where the first transparentprotective film is provided.
 41. The method for producing apressure-sensitive adhesive optical film according to claim 40, whereinthe first transparent protective film has a thickness of 60 μm or less.42. The method for producing a pressure-sensitive adhesive optical filmaccording to claim 40, wherein the polarizing plate has first and secondtransparent protective films on both sides of the polarizer, and atleast one of the first and second transparent protective films has athickness of 60 μm or less.
 43. The method for producing apressure-sensitive adhesive optical film according to claim 40, whereinthe polarizer has a thickness of 10 μm or less.
 44. The method forproducing a pressure-sensitive adhesive optical film according to claim37, wherein one of the optical films is a polarizing plate comprising apolarizer and a first transparent protective film provided on one sideof the polarizer or first and second transparent protective filmsprovided on both sides of the polarizer, the first transparentprotective film has a haze value of 15% or less, the pressure-sensitiveadhesive layer is provided on a side of the polarizing plate opposite toa side where the first transparent protective film is provided, and atleast one of the other optical film or films is a retardation plate. 45.The method for producing a pressure-sensitive adhesive optical filmaccording to claim 44, wherein the retardation plate has a thickness of60 μm or less.
 46. The method for producing a pressure-sensitiveadhesive optical film according to claim 25, wherein the optical film isa polarizing plate comprising a polarizer and a first transparentprotective film provided on one side of the polarizer or first andsecond transparent protective films provided on both sides of thepolarizer, the first transparent protective film has a haze value of 15%or less, and the pressure-sensitive adhesive layer is provided on a sideof the polarizing plate opposite to a side where the first transparentprotective film is provided.
 47. The method for producing apressure-sensitive adhesive optical film according to claim 46, whereinthe first transparent protective film has a thickness of 60 μm or less.48. The method for producing a pressure-sensitive adhesive optical filmaccording to claim 46, wherein the polarizing plate has first and secondtransparent protective films on both sides of the polarizer, and atleast one of the first and second transparent protective films has athickness of 60 μm or less.
 49. The method for producing apressure-sensitive adhesive optical film according to claim 46, whereinthe polarizer has a thickness of 10 μm or less.
 50. The method forproducing a pressure-sensitive adhesive optical film according to claim25, wherein the optical film is a retardation plate.
 51. The method forproducing a pressure-sensitive adhesive optical film according to claim50, wherein the retardation plate has a thickness of 60 μm or less. 52.The method for producing a pressure-sensitive adhesive optical filmaccording to claim 25, wherein the optical film has a haze value of 15%or less.
 53. The method for producing a pressure-sensitive adhesiveoptical film according to claim 52, wherein the optical film is intendedto be bonded to a front face plate or a touch panel.
 54. The method forproducing a pressure-sensitive adhesive optical film according to claim52, wherein the optical film has a thickness of 60 μm or less.
 55. Themethod for producing a pressure-sensitive adhesive optical filmaccording to claim 52, wherein the optical film is a surface treatmentfilm.
 56. The method for producing a pressure-sensitive adhesive opticalfilm according to claim 25, wherein the pressure-sensitive adhesivecoating liquid has a viscosity Y (P) of 2 to 160 P, and the coating hasa thickness X (μm) of 20 to 250 μm.
 57. The method for producing apressure-sensitive adhesive optical film according to claim 38, whereineach of the at least two pressure-sensitive adhesive layers has athickness (μm) standard deviation of 0.12 μm or less.
 58. The method forproducing a pressure-sensitive adhesive optical film according to claim38, wherein one of the optical films is a polarizing plate comprising apolarizer and a first transparent protective film provided on one sideof the polarizer or first and second transparent protective filmsprovided on both sides of the polarizer, the first transparentprotective film has a haze value of 15% or less, and thepressure-sensitive adhesive layer is provided on a side of thepolarizing plate opposite to a side where the first transparentprotective film is provided.
 59. The method for producing apressure-sensitive adhesive optical film according to claim 58, whereinthe first transparent protective film has a thickness of 60 μm or less.60. The method for producing a pressure-sensitive adhesive optical filmaccording to claim 58, wherein the polarizing plate has first and secondtransparent protective films on both sides of the polarizer, and atleast one of the first and second transparent protective films has athickness of 60 μm or less.
 61. The method for producing apressure-sensitive adhesive optical film according to claim 58, whereinthe polarizer has a thickness of 10 μm or less.
 62. The method forproducing a pressure-sensitive adhesive optical film according to claim38, wherein one of the optical films is a polarizing plate comprising apolarizer and a first transparent protective film provided on one sideof the polarizer or first and second transparent protective filmsprovided on both sides of the polarizer, the first transparentprotective film has a haze value of 15% or less, the pressure-sensitiveadhesive layer is provided on a side of the polarizing plate opposite toa side where the first transparent protective film is provided, and atleast one of the other optical film or films is a retardation plate. 63.The method for producing a pressure-sensitive adhesive optical filmaccording to claim 62, wherein the retardation plate has a thickness of60 μm or less.